During its long history, Istanbul had previously served as the capital of the Roman Empire (330–c.395), Byzantine Empire (c.395–1204 & 1261–1453), the Latin Empire (1204–1261), and the Ottoman Empire (1453–1922). Thereafter, the new Republic of Turkey, moved their capital to Ankara during the Turkish War of Independence. Istanbul was chosen as a European Capital of Culture for 2010 and European Capital of Sports for 2012.^[9] The historic areas of the city were added to the UNESCO World Heritage List in 1985.

Byzantium (Greek: Βυζάντιον, Byzántion) is the first known name of the city. Around 660 BC,^{[note 1]} Greek settlers from the city-state of Megara founded a Doric colony on the present-day Istanbul, and named the new colony after their king, Byzas.^[16] After Constantine I (Constantine the Great) made the city the new eastern capital of the Roman Empire in 330 AD, the city became widely known as Constantinopolis or Constantinople, which, as the Latinised form of "Κωνσταντινούπολις" (Kōnstantinoúpolis), means the "City of Constantine".^[17] He also attempted to promote the name Nea Roma ("New Rome"), but this never caught on.^[18] Constantinople remained the official name of the city throughout the Byzantine period, and the most common name used for it in the West until the establishment of the Republic of Turkey.

By the 19th century, the city had acquired a number of names used by either foreigners or Turks. Europeans often used Stamboul alongside Constantinople to refer to the whole of the city, but Turks used the former name only to describe the historic peninsula between the Golden Horn and the Sea of Marmara. Pera was used to describe the area between the Golden Horn and the Bosphorus, but Turks also used the name Beyoğlu, which is still in use today.^[19] However, with the Turkish Postal Service Law of 28 March 1930, the Turkish authorities formally requested foreigners to adopt İstanbul, a name in existence since the 10th century,^[20] as the sole name of the city within their own languages.^[21]

Etymologically, the name "İstanbul" (Turkish pronunciation: [isˈtanbuɫ], colloquially [ɯsˈtambuɫ]) derives from the Medieval Greek phrase "εἰς τὴν Πόλιν" [is tin ˈpolin] or, in the Aegean dialect, "εἰς τὰν Πόλιν" [is tan ˈpolin] (Modern Greek "στην Πόλη" [stin ˈpoli]), which means "in the city" or "to the city".^[17][20] In modern Turkish, the name is written "İstanbul", with a dotted İ, as the Turkish alphabet distinguishes between a dotted and dotless I. Also, while in English the stress is on the first syllable ("Is"), in Turkish it is on the second syllable ("tan"). Like Rome, Istanbul has been called "The City of Seven Hills" because the oldest part of the city is supposedly built on seven hills, each of which bears a historic mosque.

Recent construction of the Marmaray tunnel unearthed a Neolithic settlement underneath Yenikapı on Istanbul's peninsula. Dating back to the 7th millennium BC, before the Bosphorus was even formed, the discovery indicated that the peninsula was settled thousands of years earlier than previously thought.^[23] Thracian tribes established two settlements—Lygos and Semistra—on the Sarayburnu, near where Topkapı Palace now stands, between the 13th and 11th centuries BC. On the Asian side, artifacts have been found in Fikirtepe (present-day Kadıköy) that date back to the Chalcolithic period.^[24] The same location was the site of a Phoenician trading post at the beginning of the 1st millennium BC as well as the town of Chalcedon, which was established by Greek settlers from Megara in 685 BC.

However, the history of Istanbul generally begins around 660 BC,^{[note 1]} when the settlers from Megara, under the command of King Byzas, established Byzantion (Latinised as Byzantium) on the European side of the Bosphorus. By the end of the century, an acropolis was established at the former locations of Lygos and Semistra, on the Sarayburnu.^[16] The city experienced a brief period of Persian rule at the turn of the 5th century BC, but the Greeks recaptured it during the Greco-Persian Wars.^[25] Byzantium then continued as part of the Athenian League and its successor, the Second Athenian Empire, before ultimately gaining independence in 355 BC.^[26] Long protected by the Roman Republic, Byzantium officially became a part of the Roman Empire in AD 73.

Byzantium's decision to side with the usurper Pescennius Niger against Roman Emperor Septimus Severus cost it dearly; by the time it surrendered at the end of 195, two years of siege had left the city devastated.^[27] Still, five years later, Severus began to rebuild Byzantium, and the city regained—and, by some accounts, surpassed—its previous prosperity.

When Constantine I defeated Licinius at the Battle of Chrysopolis in September 324, he effectively became the emperor of the whole of the Roman Empire.^[29] Just two months later, Constantine laid out the plans for a new, Christian city to replace Byzantium. Intended to replace Nicomedia as the eastern capital of the empire, the city was named Nea Roma (New Rome); however, most simply called it Constantinople ("the city of Constantine"), a name that persisted into the 20th century.^[30] Six years later, on 11 May 330, Constantinople was proclaimed the capital of an empire that eventually became known as the Byzantine Empire or Eastern Roman Empire.

The establishment of Constantinople served as one of Constantine's most lasting accomplishments, shifting Roman power eastward and becoming a center of Greek culture and Christianity.^[31][32] Numerous churches were built across the city, including the Hagia Sofia, which remained the world's largest cathedral for a thousand years.^[33] The Ecumenical Patriarchate of Constantinople developed in the city, and its leader is still one of the foremost figures in the Greek Orthodox Church. Constantinople's location also ensured its existence would stand the test of time; for many centuries, its walls and seafront protected Europe against invaders from the east as well as from the advance of Islam.^[32] During most of the Middle Ages and the latter part of the Byzantine period, Constantinople was the largest and wealthiest city in the western world

Constantinople began to decline after the Fourth Crusade, during which it was sacked and pillaged.^[36] The city subsequently became the center of the Latin Empire, created by Catholic crusaders to replace the Orthodox Byzantine Empire, which was divided into splinter states.^[37] However, the Latin Empire was short-lived, and the Byzantine Empire was restored, weakened, in 1261.^[38] Constantinople's churches, defenses, and basic services were in disrepair,^[39] and its population had dwindled to forty thousand from nearly half a million during the 9th century.^[40][41]

Various economic and military policies instituted by Andronikos II, such as the reduction of forces, weakened the empire and left it more vulnerable to attack.^[42] In the mid-14th century, the Ottoman Turks began a strategy by which they took smaller towns and cities over time, cutting off Constantinople's supply routes and strangling it slowly.^[43] Finally, on 29 May 1453, after an eight-week siege (during which the last Roman Emperor, Constantine XI, was killed), Sultan Mehmed II "the Conqueror" captured Constantinople and declared it the new capital of the Ottoman Empire.^[44][45] Hours later, the sultan rode to the Hagia Sofia and summoned an imam to proclaim the Islamic creed, converting the grand cathedral into an imperial mosque.

Following the fall of Constantinople, Mehmed II immediately set out to revitalize the city, now also known as Istanbul. He invited and forcibly resettled many Muslims, Jews, and Christians from other parts of Anatolia into the city, creating a cosmopolitan society that persisted through much of the Ottoman period.^[47] By the end of the century, Istanbul had returned to a population of two hundred thousand, making it the second-largest city in Europe.^[48] Meanwhile, Mehmed II repaired the city's damaged infrastructure and began to build the Grand Bazaar. Also constructed during this period was Topkapı Palace, which served as the official residence of the sultan for four hundred years.

The Ottomans quickly transformed Istanbul from a bastion of Christianity to a symbol of Islamic culture. Religious foundations were established to fund the construction of grand imperial mosques, often adjoined by schools, hospitals, and public baths.^[49] Suleiman the Magnificent's reign from 1520 to 1566 was a period of especially great artistic and architectural achievements; chief architect Mimar Sinan designed the Süleymaniye Mosque and other grand buildings in the city, while Ottoman arts of ceramics, calligraphy and miniature flourished.^[50] The total population of Istanbul amounted to 570,000 by the end of the 18th century.

A period of rebellion at the start of the 19th century led to the rise of the progressive Sultan Mahmud II and eventually the Tanzimat period, which produced reforms that aligned the empire along Western European standards.^[52][53] Bridges across the Golden Horn were constructed during this period,^[54] and Istanbul was connected to the rest of the European railway network in the 1880s.^[55] The Tünel, one of the world's oldest subterranean urban rail lines, opened in 1875;^[56] other modern facilities, such a stable water network, electricity, telephones, and trams, were gradually introduced to Istanbul over the following decades, although later than to other European cities.

Still, the modernization efforts were not enough to forestall the decline of the Ottoman regime. The early 20th century saw the Young Turk Revolution, which disposed of Sultan Abdul Hamid II, and a series of wars that plagued the ailing empire's capital.^[58] The last of these, World War I, resulted in the British, French, and Italian occupation of Istanbul. The final Ottoman sultan, Mehmed VI, was exiled in November 1922; the following year, the occupation of Istanbul ended with the signing of the Treaty of Lausanne and the recognition of the Republic of Turkey, which was declared by Mustafa Kemal Atatürk on 29 October 1923.

In the early years of the republic, Istanbul was overlooked in favor of the country's new capital, Ankara. However, starting from the late 1940s and early 1950s, Istanbul underwent great structural change, as new public squares (such as Taksim Square), boulevards, and avenues were constructed throughout the city, sometimes at the expense of historical buildings.^[60] The population of Istanbul began to rapidly increase in the 1970s, as people from Anatolia migrated to the city to find employment in the many new factories that were built on the outskirts of the sprawling metropolis. This sudden, sharp rise in the city's population caused a large demand for housing development, and many previously outlying villages and forests became engulfed into the greater metropolitan area of Istanbul.

Istanbul is located in northwestern Turkey within the Marmara Region on a total area of 5,343 square kilometers (2,063 sq mi).^{[note 2]} The Bosphorus, which connects the Sea of Marmara to the Black Sea, divides the city into a European side, comprising the historic and economic centers, and an Asian, Anatolian side; as such, Istanbul is the only bi-continental city in the world. The city is further divided by the Golden Horn, a natural harbor bounding the peninsula where the former Byzantium and Constantinople were founded. In the late-19th century, a wharf was constructed in Galata at the mouth of the Golden Horn, replacing a sandy beach that once formed part of the inlet's coastline.^[62] The confluence of the Sea of Marmara, the Bosphorus, and the Golden Horn at the heart of present-day Istanbul has deterred attacking forces for thousands of years and still remains a prominent feature of the city's landscape.

The historic peninsula is said to be built on seven hills, each topped by an imperial mosque, surrounded by 22 kilometers (14 mi) of city walls; the largest of these hills is the site of Topkapı Palace on the Sarayburnu.^[63] Rising from the opposite side of the Golden Horn is another, conical hill, where the modern Beyoğlu district is situated. Because of the topography, buildings were once constructed with the help of terraced retaining walls (some of which are still visible in older parts of the city), and roads in Beyoğlu were laid out in the form of steps.^[62] Üsküdar on the Asian side exhibits similarly hilly characteristics, with the terrain gradually extending down to the Bosphorus coast, but the landscape in Şemsipaşa and Ayazma is more abrupt, akin to a promontory. The highest point in Istanbul is Çamlıca Hill (also on the Asian side), with an altitude of 288 meters (945 ft).

Istanbul is situated near the North Anatolian Fault on the boundary between the African and Eurasian plates. This fault zone, which runs from northern Anatolia to the Sea of Marmara, has been responsible for several deadly earthquakes throughout the city's history. Among the most devastating of these seismic events was the 1509 earthquake, which caused a tsunami that broke over the walls of the city, destroyed over 100 mosques, and killed more than 10,000 people. More recently, in 1999, an earthquake with its epicenter in nearby İzmit left 17,000 people dead, including 1,000 people in Istanbul's suburbs.^[64] Istanbulites remain concerned that an even more catastrophic seismic event may be in Istanbul's near future, as thousands of structures recently built to accommodate the city's rapidly increasing population may not have been constructed properly.^[64] Seismologists say the risk of a 7.6-magnitude earthquake striking Istanbul by 2030 is greater than sixty percent.

Istanbul has a Mediterranean climate according to the Köppen climate classification system,^[67] although its climate becomes more oceanic toward the north.^[68]

In summer the weather in Istanbul is hot and humid, with the temperature in July and August averaging 23 °C (73 °F).^[69] Summers are relatively dry, but rainfall is significant during that season. Extreme heat, however, is uncommon, as temperatures rise above 32 °C (90 °F) just five times each year.^[70] During winter it is cold, wet and often snowy, with the temperature in January and February averaging 5 °C (41 °F).^[69] Snowfalls tend to be heavy, but the snowcover and temperatures below the freezing point rarely last more than a few days. Spring and autumn are mild, but are unpredictable and often wet, and can range from chilly to warm, however the nights are chilly.

Istanbul has an annual average precipitation of 843.9 mm (33 in) which does occur all year round.

The humidity of the city is constantly high which makes the air feel much harsher than the actual temperatures, particularly during summer and winter, even though the temperatures during both seasons are rarely extreme.

Istanbul also tends to be a windy city, having an average wind speed of 18 km/h (11 mph).

Due to the city's huge size, topography and maritime influences, Istanbul exhibits a multitude of distinct microclimates.

The highest recorded temperature was 40.5 °C (105 °F) on 12 July 2000, and the lowest recorded temperature was −16.1 °C (3 °F) on 9 February 1927.

Istanbul has thirty-nine districts administered by the Istanbul Metropolitan Municipality (MMI).^[3] The district of Fatih, which includes the neighborhood and former district of Eminönü, is among the most central of these, residing on the historic peninsula south of the Golden Horn. The district corresponds to what was until the Ottoman conquest the whole of the city, across from which stood the Genoese citadel of Galata in the late Byzantine era. Those Genoese fortifications were largely demolished in the 19th century, leaving only the Galata Tower, to make way for northward expansion of the city.^[77] Galata is now a part of the Beyoğlu district, which forms Istanbul's commercial and entertainment center and includes İstiklal Avenue and Taksim Square.^[78]

Dolmabahçe Palace, the seat of government during the late Ottoman period, is located in Beşiktaş, just north of Beyoğlu, across from BJK İnönü Stadium, home to Turkey's oldest football club.^[79] The former village of Ortaköy is situated within Beşiktaş and provides its name to the Ortaköy Mosque, along the Bosphorus near the First Bosphorus Bridge. Lining the shores of the Bosphorus north of there are yalıs, luxurious chalet mansions originally built by 19th-century aristocrats and elites as summer homes.^[80] Today, some are homes within the city's most exclusive neighborhoods, including Bebek. Further inland, between the Bosphorus Bridge and the Fatih Sultan Mehmet (Second Bosphorus) Bridge, are Levent, Maslak, and Mecidiyeköy, Istanbul's primary economic centers. Officially part of the Beşiktaş and Şişli districts, they contain Istanbul's tallest buildings and the headquarters of Turkey's largest companies.

Like Beyoğlu, the districts of Üsküdar and Kadıköy on the Asian side were originally separate cities, Chrysopolis and Chalcedon, respectively. During the Ottoman period, they continued to remain outside the scope of urban Istanbul, serving as tranquil outposts with seaside yalıs and gardens. However, during the second half of the 20th century, the Asian side experienced massive urban growth, owning in part to the development of Bağdat Avenue into an upscale shopping hub similar to İstiklal Avenue on the European side. The fact that these areas were largely empty until the 1960s also provided the chance for developing better infrastructure and tidier urban planning when compared with most other residential areas in the city. While now officially parts of Istanbul, much of the Asian side of the Bosphorus, which accounts for one third of the city's population, functions as a suburb of the economic and commercial centers in European Istanbul.

As a result of Istanbul's exponential growth during the 20th century, a significant portion of the city's outskirts comprised gecekondus (a Turkish term meaning built overnight), referring to the illegally constructed squatter buildings run rampant outside the centers of the country's largest cities. At present, some gecekondu areas are being gradually demolished and replaced by modern mass-housing compounds.

Istanbul is primarily known for its Ottoman architecture, but its buildings reflect the various peoples and empires that have ruled its predecessors. Genoese, Byzantine, Roman, and even Greek forms of architecture remain visible in Istanbul alongside their Ottoman counterparts. Similarly, while imperial mosques dominate much of the city's skyline, the city is also home to a number of historic churches and synagogues.

The Galata Bridge can be seen in the centre of the picture. The Seraglio Point where the Topkapı Palace is located is seen at the left tip of the historic peninsula; followed by (left to right) the Hagia Sophia, the Sultan Ahmed Mosque, the Yeni Mosque near the Galata Bridge, the Beyazıt Tower rising high in the background, and the Süleymaniye Mosque at far right, among others. The Sea of Marmara and the Princes' Islands are seen in the background, on the horizon. At the extreme left of the picture, the district of Kadıköy (ancient Chalcedon) on the Asian side of the city can be seen. Behind the Galata Bridge, towards the horizon, the Column of Constantine (which was surrounded by iron bars for restoration) rises.

More than two thousand years following the departure of the Greeks, few examples of Istanbul's Greek architecture have survived. Remains of Byzantium's acropolis are still visible within the confines of Topkapı Palace, but perhaps the most prominent relic of the Greek era is Maiden's (Leander's) Tower. Residing on an islet in the Bosphorus just off the coast of Üsküdar, Maiden's Tower was first built by the Greeks in 408 BC to guide ships within the strait. Since then, however, the tower has undergone a number of enlargements and restorations, most notably by Byzantine Emperor Alexius Comnenus in 1104 AD, thereby rendering its connection to Greek architecture tenuous. Either way, despite serving as a lighthouse for several centuries, Maiden's Tower today merely serves as a popular vantage point from which to view the historic city.

Examples of Roman architecture have proved themselves to be more durable. Obelisks from the Hippodrome of Constantinople, modeled after the Circus Maximus in Rome, are still visible in Sultanahmet Square. A section of the Valens Aqueduct, constructed in the late 4th century to carry water to the city, stands relatively intact over 920 meters (3,000 ft) in the west of the Fatih district. Similarly, the Walls of Constantinople, which were erected in stages well into the Byzantine period, are still visible along much of their original 22-kilometer (14 mi) course. Finally, the Column of Constantine, erected in 330 AD to mark the new Roman capital, still stands not far from the Hippodrome.

Early Byzantine architecture followed the classical Roman model of domes and arches, but further improved these architectural concepts, as in the Church of the Saints Sergius and Bacchus, which signaled an improvement in the design of domed buildings. The oldest surviving Byzantine church in Istanbul that has preserved its original form through the centuries (albeit partially in ruins) is the Stoudios (İmrahor) Monastery, which was built in 462. Other extant structures from the early Byzantine period include the Hagia Irene, initially the first church in the new capital, and the Prison of Anemas, which was incorporated into the city walls at the western suburb of Blachernae. After the recapture of Constantinople in 1261, the Byzantines constructed two of their most important churches, Chora Church and Pammakaristos Church. Across the Golden Horn, the Genoese contributed Galata Tower, then the highest point in the citadel of Galata and today a landmark in the neighborhood of the same name.

Still, the pinnacle of Byzantine architecture, and one of Istanbul's most iconic structures, is the Hagia Sophia, built between 532 and 537. Topped by a dome 31 meters (102 ft) in diameter, the Hagia Sofia stood as the largest cathedral for more than a thousand years, until the completion of the Cathedral of Seville. The Ottomans later covered its Christian mosaics and added Islamic elements, including four minarets, converting the magnificent cathedral into a mosque. Today, it is neither, as its mosaics were uncovered and the impressive edifice converted into a museum in the 1930s.

Among the oldest extant examples of Ottoman architecture in Istanbul are the Anadoluhisarı and Rumelihisarı fortresses, which helped block sea traffic aimed at assisting the Byzantines during the Turkish siege of the city.^[81] Over the next four centuries, the Ottomans continued to make an indelible impression on the skyline of Istanbul, building towering mosques and ornate palaces. These grand imperial mosques include Sultan Ahmed Mosque (the Blue Mosque), Süleymaniye Mosque, and Yeni Mosque, all of which were built at the peak of the Ottoman Empire, in the 16th and 17th centuries.

In the following centuries, and especially after the Tanzimat reforms, Ottoman architecture was supplanted by European styles. In contrast to the traditional elements of Topkapı Palace and the mosques on the historic peninsula, Dolmabahçe Palace, Yıldız Palace, and Ortaköy Mosque in Beşiktaş and Beylerbeyi Palace across the Bosphorus in Üsküdar are clearly of Neo-Baroque style. At the same time, the areas around İstiklal Avenue were filled with grandiose European embassies and rows of buildings in European (mostly Neoclassical and, later, Art Nouveau) style started to appear along the avenue. Istanbul was one of the major centers of the Art Nouveau movement in the late-19th and early-20th centuries, with famous architects of this style building palaces and mansions in the city.

The mayor of Istanbul, currently Kadir Topbaş, serves as the prefect of the city.^[82] The governor of Istanbul province is Muammer Güler.^[83]

Istanbul is a home rule city and municipal elections are mainly partisan. The metropolitan model of governance has been used with the establishment of metropolitan administration in 1930. The metropolitan council is responsible for all authority when it comes to making city decisions.^[84]

The metropolitan government structure consists of three main organs: (1) The Metropolitan Mayor (elected every five years), (2) The Metropolitan Council (decision making body with the mayor, district Mayors, and one fifth of the district municipal councillors), (3) The metropolitan executive committee. There are three types of local authorities: (1) municipalities, (2) special provincial administrations, (3) village administrations. Among the local authorities, municipalities are gaining greater importance with the rise in urbanisation.

The current Istanbul Metropolitan Municipality City Hall building in the Saraçhane quarter of the Fatih district, the construction of which began on 17 December 1953 and was completed and inaugurated on 26 May 1960, will soon be demolished and replaced by a new building, designed by Istanbul-based Arolat Architects.

The population of the metropolis more than tripled during the 25 years between 1980 and 2005. Roughly 70% of all Istanbulites live in the European section and around 30% in the Asian section. Due to high unemployment in the southeast of Turkey, many people from that region migrated to Istanbul, where they established themselves in the outskirts of the city. Migrants, predominantly from eastern Anatolia arrive in Istanbul expecting improved living conditions and employment, which usually end with little success. This results each year with new gecekondus at the outskirts of the city, which are later developed into neighbourhoods and integrated into the greater metropolis.

The city has a population of 11,372,613 residents according to the latest count as of 2007,^[86] and is one of the largest cities in the world today. The rate of population growth in the city is currently at 3.45% a year on average, mainly due to the influx of people from the surrounding rural areas. Istanbul's population density of 2,742 people per square mile (1,700 per square km) far exceeds Turkey's 130 people per square mile (81 people per square km).^[87]

During the early Middle Ages, Istanbul was the largest city in the world, and has been one of the world's largest and most important cities during much of its history (excepting the period of collapse of the Byzantine Empire, before the Ottomans). Its geopolitical significance since ancient times brought representatives of ethnic groups from all over Europe, Asia, and Africa. Throughout its history the ethnic Greek and then Turkish populations have assimilated these groups throughout the city's history.

The following overview shows the numbers of inhabitants by year^{[citation needed]}. Population tallies up to 1914 are estimated with variations of up to 50% depending upon researcher. The numbers from 1927 to 2000 are results of censuses. The numbers of 2005 and 2006 are based on computer simulation forecasts. The doubling of the population of Istanbul between 1980 and 1985 is due to a natural increase in population as well as the expansion of municipal limits.

The urban landscape of Istanbul is shaped by many communities. The religion with the largest community of followers is Islam. Religious minorities include Greek Orthodox Christians, Armenian Christians, Catholic Levantines and Sephardic Jews. According to the 2000 census, there were 2,691 active mosques, 123 active churches and 26 active synagogues in Istanbul; as well as 109 Muslim cemeteries and 57 non-Muslim cemeteries. Some districts used to have sizeable populations of these ethnic groups, such as the Kumkapı district, which had a sizeable Armenian population; the Balat district, which had a sizeable Jewish population; the Fener district, which had a sizeable Greek population; and some neighbourhoods in the Nişantaşı and Beyoğlu districts that had sizeable Levantine populations. Very few remain in these districts, as they either emigrated or moved to other districts. In some quarters, such as Kuzguncuk, an Armenian church sits next to a synagogue, and on the other side of the road a Greek Orthodox church is found beside a mosque.

The seat of the Patriarch of Constantinople, spiritual leader of the Greek Orthodox Church and first patriarch of the Eastern Orthodox communion, is located in the Fener (Phanar) district. Also based in Istanbul are the archbishop of the Turkish-Orthodox community, an Armenian archbishop, and the Turkish Grand-Rabbi. A number of places reflect past movements of different communities into Istanbul, most notably Arnavutköy (Albanian village), Polonezköy (Polish village) and Yenibosna (New Bosnia).

The Muslims are by far the largest religious group in Istanbul. Among them, the Sunnis form the most populous sect, while a number of the local Muslims are Alevis. In 2007 there were 2,944 active mosques in Istanbul.^[88]

Istanbul was the final seat of the Islamic Caliphate, between 1517 and 1924, when the Caliphate was dissolved and its powers were handed over to the Turkish Parliament. On 2 September 1925, the tekkes and tarikats were banned, as their activities were deemed incompatible with the characteristics of the secular democratic Republic of Turkey; particularly with the secular education system and the laicist state's control over religious affairs through the Religious Affairs Directorate. Most followers of Sufism and other forms of Islamic mysticism practiced clandestinely afterwards, and some of these sects still boast numerous followers. To avoid the still active prohibition, these organisations represent themselves as "cultural associations

The city has been the seat of the Ecumenical Patriarchate since the 4th century AD, and continues to serve as the seat of some other Orthodox churches, such as the Turkish Orthodox Church and the Armenian Patriarchate. The city was formerly also the seat of the Bulgarian Exarchate, before its autocephaly was recognised by other Orthodox churches.

The everyday life of the Christians, particularly the Greeks and Armenians living in Istanbul changed significantly following the bitter conflicts between these ethnic groups and the Turks during the fall of the Ottoman Empire, which began in the 1820s and continued for a century. The conflicts reached their culmination in the decade between 1912 and 1922; during the Balkan Wars, the First World War and the Turkish War of Independence. The Christian population declined from 450,000 to 240,000 between 1914 and 1927.^[89] Today, most of Turkey's remaining Greek and Armenian minorities live in or near Istanbul. The number of the local Turkish Armenians in Istanbul today amount to approximately 45,000^[90] (not including the nearly 40,000 Armenian workers in Turkey who came from Armenia after 1991 and mostly live and work in Istanbul);^[91] while the Greek community, which amounted to 150,000 citizens in 1924,^[92] currently amounts to approximately 4,000 citizens.^[90] There are also 60,000 Istanbulite Greeks who currently live in Greece but continue to retain their Turkish citizenship.^[90]

The Sephardic Jews have lived in the city for over 500 years. They fled the Iberian Peninsula during the Spanish Inquisition of 1492, when they were forced to convert to Christianity after the fall of the Moorish Kingdom of Andalucia. The Ottoman Sultan Bayezid II (1481–1512) sent a sizable fleet to Spain under the command of Kemal Reis to save the Sephardic Jews. At that point in the Caliphate's history it was a beacon of tolerance compared to most of Christendom. More than 200,000 Jews fled first to Tangier, Algiers, Genova, and Marseille, later to Salonica, and finally to Istanbul. The Sultan granted over 93,000 of these Spanish Jews to take refuge in the Ottoman Empire. Another large group of Sephardic Jews came from southern Italy, which was under Spanish control. The İtalyan Sinagogu (Italian Synagogue) in Galata is mostly frequented by the descendants of these Italian Jews in Istanbul, where more than 20,000 Sephardic Jews still remain today. There are about 20 synagogues, the most important of them being the Neve Shalom Synagogue inaugurated in 1951, in the Beyoğlu quarter.

Apart from being the largest city and former political capital of the country, Istanbul has always been the centre of Turkey's economic life because of its location as a junction of international land and sea trade routes. Istanbul is also Turkey's largest industrial centre. It employs approximately 20% of Turkey's industrial labour and contributes 38% of Turkey's industrial workspace. Istanbul and its surrounding province produce cotton, fruit, olive oil, silk, and tobacco. Food processing, textile production, oil products, rubber, metal ware, leather, chemicals, pharmaceuticals, electronics, glass, machinery, automotive, transport vehicles, paper and paper products, and alcoholic drinks are among the city's major industrial products. According to Forbes magazine, Istanbul had a total of 35 billionaires as of March 2008, ranking fourth in the world.

Originally established as the Ottoman Stock Exchange (Dersaadet Tahvilat Borsası) in 1866, and reorganised to its current structure at the beginning of 1986, the Istanbul Stock Exchange (ISE) is the sole securities market of Turkey.^[94] During the 19th century and early 20th century, Bankalar Caddesi (Banks Street) in Galata was the financial centre of the Ottoman Empire, where the headquarters of the Ottoman Central Bank (established as the Bank-ı Osmanî in 1856, and later reorganised as the Bank-ı Osmanî-i Şahane in 1863)^[95] and the Ottoman Stock Exchange (1866) were located.^[96] Bankalar Caddesi continued to be Istanbul's main financial district until the 1990s, when most Turkish banks began moving their headquarters to the modern central business districts of Levent and Maslak.^[96] In 1995, the Istanbul Stock Exchange moved to its current building in the İstinye quarter.

Today, the city generates 55% of Turkey's trade and 45% of the country's wholesale trade, and generates 21.2% of Turkey's gross national product. Istanbul contributes 40% of all taxes collected in Turkey and produces 27.5% of Turkey's national product. In 2005 the City of Istanbul had a GDP of $133 billion.^[98] In 2005 companies based in Istanbul made exports worth $41,397,000,000 and imports worth $69,883,000,000; which corresponded to 56.6% and 60.2% of Turkey's exports and imports, respectively, in that year.^[99]

Istanbul is one of the most important tourism spots of Turkey. There are thousands of hotels and other tourist oriented industries in the city, catering to both vacationers and visiting professionals. In 2006 a total of 23,148,669 tourists visited Turkey, most of whom entered the country through the airports and seaports of Istanbul and Antalya.^[100] The total number of tourists who entered Turkey through Atatürk International Airport and Sabiha Gökçen International Airport in Istanbul reached 5,346,658, rising from 4,849,353 in 2005.^[101] Istanbul is also one of the world's major conference destinations and is an increasingly popular choice for the world's leading international associations

Istanbul holds some of the finest institutions of higher education in Turkey, including more than 35 public and private universities. Most of the reputable universities are public, but in recent years there has also been an upsurge in the number of private universities. Istanbul University, founded in 1453, is the oldest Turkish educational institution in the city,^[103] while Istanbul Technical University (1773) is the world's third-oldest technical university dedicated entirely to engineering sciences.^[104] Other prominent state universities in Istanbul include Boğaziçi University, Mimar Sinan University of Fine Arts, Yildiz Technical University and Marmara University. The major private universities in the city include Koç University, Sabancı University, Istanbul Bilgi University, Istanbul Commerce University, Bahçeşehir University, Yeditepe University, Istanbul Kültür University, and Kadir Has University. Almost all Turkish private high schools and universities in Istanbul teach in English, German or French as the primary foreign language, usually accompanied by a secondary foreign language.

Among the best public schools of Turkey, the Galatasaray Lisesi, established in 1481 as Galata Sarayı Enderun-u Hümayunu (Galata Palace Imperial School) and later known as Galatasaray Mekteb-i Sultanisi (Galatasaray School of the Sultans), is the oldest Turkish high school in Istanbul and the second oldest Turkish educational institution in the city. İstanbul Lisesi, also commonly known as İstanbul Erkek Lisesi (established in 1884), abbreviated İEL, is one of the oldest and internationally renowned public high schools of Turkey. Kuleli Military High School is the only military high school in Istanbul, located in Çengelköy district. Another important school in Turkey is Darüşşafaka which has no similar world-wide providing children opportunities around the Turkey without receiving any money from any of them. This school was built in 1873 by Darüşşafaka community. Primary person who came up with creating this school and community is Yusuf Ziya Pasha. Darüşşafaka is located in Maslak.

Anadolu Liseleri (Anatolian High Schools) were originally furnished for the Turkish children who returned home from foreign countries, such as the Üsküdar Anadolu Lisesi with German as the primary foreign language and technical instruction in German. Kadıköy Anadolu Lisesi is one of the first six special Ministry of Education Colleges established in 1950s in big cities across Turkey. Those English-medium colleges were renamed as "Anadolu Lisesi" in subsequent decades. There are also many foreign high schools in Istanbul, most of which were established in the 19th century to educate foreigners in Istanbul. Following the establishment of the Republic of Turkey, most of these schools went under the administration of the Turkish Ministry of Education, but some of them still have considerable foreign administration, such as the Liceo Italiano Statale I.M.I. (Özel İtalyan Lisesi), which is still regarded as an Italian state school by the government of Italy and continues to receive funding and teachers from Rome.^[105] Robert College established in 1863 and Üsküdar American Academy established in 1876, are other remarkable foreign schools in the city, among numerous others.

Istanbul has numerous libraries, many of which contain vast collections of historic documents from the Roman, Byzantine and Ottoman periods, as well as from other civilisations of the past. The most important libraries in terms of historic document collections include the Topkapı Palace Library, Library of the Archaeological Museum, Library of the Naval Museum, Beyazıt State Library, Nuruosmaniye Library, Süleymaniye Library, Istanbul University Library, Köprülüzade Fazıl Ahmed Paşa Library, Atatürk Library and Çelik Gülersoy Library.

The city has many public and private hospitals, clinics and laboratories within its bounds and numerous medical research centers. Many of these facilities have high technology equipment, which has contributed to the recent upsurge in "medical tourism" to Istanbul,^[106] particularly from West European countries like the United Kingdom and Germany where governments send patients with lower income to the city for the inexpensive service of high-tech medical treatment and operations.^[107] Istanbul has particularly become a global destination for laser eye surgery and plastic surgery.^[106] The city also has an Army Veterans Hospital in the military medical centre.

Pollution-related health problems increase especially in the winter, when the combustion of heating fuels increase. The rising number of new cars in the city and the slow development of public transportation often cause urban smog conditions. Mandatory use of unleaded gas was scheduled to begin only in January 2006.

Istanbul's first water supply systems date back to the foundation of the city. The two greatest aqueducts from the Roman period are the Mazulkemer Aqueduct and the Valens Aqueduct. These were built to channel water from the Halkalı area in the western edge of the city to the Beyazıt district in the city centre, which was called the Forum Tauri in the Roman period.^[109] After reaching the city centre, the water was later collected in the city's numerous cisterns, such as the famous Philoxenos (Binbirdirek) Cistern and the Basilica (Yerebatan) Cistern. Sultan Suleiman the Magnificent commissioned Mimar Sinan, his engineer and architect-in-chief, to improve the water needs of the city. Sinan constructed the Kırkçeşme Water Supply System in 1555.^[109] In later years, with the aim of responding to the ever-increasing public demand, water from various springs was channeled to the public fountains by means of small supply lines; see German Fountain.

Today, Istanbul has a chlorinated and filtered water supply and a sewage disposal system managed by the government agency İSKİ.^[110] There are also several private sector organisations distributing clean water. Electricity distribution services are covered by the state-owned TEK. The first electricity production plant in the city, Silahtarağa Termik Santrali, was established in 1914 and continued to supply electricity until 1983.^[111]

The Ottoman Ministry of Post and Telegraph was established in the city on 23 October 1840.^[112] The first post office was the Postahane-i Amire near the courtyard of Yeni Mosque.^[112] In 1876 the first international mailing network between Istanbul and the lands beyond the vast Ottoman Empire was established.^[112] In 1901 the first money transfers were made through the post offices and the first cargo services became operational.^[112] Samuel Morse received his first ever patent for the telegraph in 1847, at the old Beylerbeyi Palace (the present Beylerbeyi Palace was built in 1861–1865 on the same location) in Istanbul, which was issued by Sultan Abdülmecid who personally tested the new invention.^[113] Following this successful test, installation works of the first telegraph line between Istanbul and Edirne began on 9 August 1847.^[114] In 1855 the Telegraph Administration was established.^[112] In July 1881 the first telephone circuit in Istanbul was established between the Ministry of Post and Telegraph in Soğukçeşme and the Postahane-i Amire in Yenicami.^[114] On 23 May 1909, the first manual telephone exchange with a 50 line capacity was established in the Büyük Postane (Grand Post Office) of Sirkeci

Istanbul has two international airports: The larger one is the Atatürk International Airport located in the Yeşilköy district on the European side, about 24 kilometres (15 mi) west from the city centre. When it was first built, the airport was situated at the western edge of the metropolitan area but now lies within the city bounds. The smaller one is the Sabiha Gökçen International Airport located in the Kurtköy district on the Asian side, close to the Istanbul Park GP Racing Circuit. It is situated approximately 20 kilometres (12 mi) east of the Asian side and 45 kilometres (28 mi) east of the European city centre.

Sea transport is vital for Istanbul, as the city is practically surrounded by sea on all sides: the Sea of Marmara, the Golden Horn, the Bosphorus and the Black Sea. Many Istanbulites live on the Asian side of the city but work on the European side (or vice-versa) and the city's famous commuter ferries form the backbone of the daily transition between the two parts of the city – even more so than the two suspension bridges that span the Bosphorus. The commuter ferries, along with the high speed catamaran Seabus (Deniz Otobüsü), also form the main connection between the city and the Princes' Islands.

The first steam ferries appeared on the Bosphorus in 1837 and were operated by private sector companies.^[115] On 1 January 1851, the Şirket-i Hayriye (literally the Goodwill Company, as the Istanbul Ferry Company was originally called) was established by the Ottoman state.^[115] The Şirket-i Hayriye continued to operate the city's landmark commuter ferries until the early years of the Republican period, when they went under the direction of Türkiye Denizcilik İşletmeleri (Turkish State Maritime Lines).^[115] Since March 2006, Istanbul's traditional commuter ferries are operated by İstanbul Deniz Otobüsleri (Istanbul Sea Buses), which also operates the high speed catamaran Seabus.^[115]

İDO (İstanbul Deniz Otobüsleri – Istanbul Sea Buses) was established in 1987 and operates the high speed catamaran Seabuses that run between the European and Asian parts of Istanbul—and also connect the city with the Princes' Islands and other destinations in the Sea of Marmara. The Yenikapı High Speed Car Ferry Port on the European side, and the Pendik High Speed Car Ferry Port on the Asian side, are where the high speed catamaran "car ferries" are based. The car ferries that operate between Yenikapı (on the European side of Istanbul) and Bandırma reduce the driving time between Istanbul and İzmir and other major destinations on Turkey's Aegean coast by several hours; while those that operate between Yenikapı or Pendik (on the Asian side of Istanbul) and Yalova significantly reduce the driving time between Istanbul and Bursa or Antalya.

The port of Istanbul is the most important one in the country. The old port on the Golden Horn serves primarily for personal navigation, while Karaköy port in Galata is used by the large cruise liners. Regular services as well as cruises from both Karaköy and Eminönü exist to several port cities in the Mediterranean Sea and Black Sea. Istanbul's main cargo port is located in the Harem district on the Asian side of the city. Istanbul also has several marinas of varying size for personal navigation, the largest of which are the Ataköy Marina on the European side and Kalamış Marina on the Asian side.

The State Road D.100 and the European route E80, the Trans European Motorway (TEM) O-3 are the two main motorway connections between Europe and Turkey. The motorway network around Istanbul is well developed and is constantly being extended. Motorways lead east to Ankara and west to Edirne. There are also two express highways circling the city. The older one, the O-1, is mostly used for inner city traffic; while the more recent one, the O-2, is mostly used by intercity or intercontinental traffic.

The Bosphorus Bridge on the O-1 and the Fatih Sultan Mehmet Bridge on the O-2 establish the motorway connection between the European and the Asian sides of the Bosphorus. The southern and northern shores of the Golden Horn, an inlet of the Bosphorus on the European side of the city, are connected through the Galata Bridge, the Atatürk Bridge and the Haliç Bridge; the latter also being a part of the O-1 motorway network.

Büyükdere Avenue is the main artery that runs through the central business districts of Levent and Maslak on the European side, and is also accessible through a number of subway stations. At the point where the O-1 motorway junctions and tunnels between the quarters of Gayrettepe and Zincirlikuyu come together, Büyükdere Avenue connects with Barbaros Boulevard, which descends towards the ferry port of Beşiktaş. There it connects with the coastal highway that runs along the European shore of the Bosphorus, from Eminönü in the south to Sarıyer in the north.

In 1883, a Belgian entrepreneur, Georges Nagelmackers, began a rail service between Paris and Istanbul, using a steamship to ferry passengers from Varna to Constantinople. In 1889, a rail line was completed going directly from Istanbul to Bucharest, making the whole journey via land possible. The route was known as the Orient Express, made even more famous by the works of Agatha Christie and Graham Greene.^[116]

Today, the Sirkeci Terminal of the Turkish State Railways (TCDD), which was originally opened in 1890 as the terminus of the Orient Express, is the terminus of all the lines on the European side and the main connection node of the Turkish railway network with the rest of Europe.

Currently, international connections are provided by the line running between Istanbul and Thessaloniki, Greece, and the Bosphorus Express serving daily between Sirkeci and Bucharest, Romania. Lines to Sofia, Belgrade, Budapest are established over the Bosphorus Express connection to Bucharest.

Beyond the Bosphorus, the Haydarpaşa Terminal on the Asian side serves lines running several times daily to Ankara, and less frequently to other destinations in Anatolia. The railway networks on the European and Asian sides are currently connected by the train ferry across the Bosphorus, which will be replaced by an underwater tunnel connection with the completion of the Marmaray project, scheduled for 2012. Marmaray (Bosphorus Rail Tunnel) will also connect the metro lines on the European and Asian parts of the city. Inaugurated in 1908, the Haydarpaşa Terminal was originally opened as the terminus of the Istanbul-Konya-Baghdad and Istanbul-Damascus-Medina railways.

A suburban railway line runs between the main train station of the European part, the Sirkeci Terminal, and the Halkalı district towards the west of the city centre, with 18 stations along its 30 km length. A single trip takes 48 minutes. Another suburban line runs on the Anatolian part from the main train station, the Haydarpaşa Terminal, to Gebze at the eastern end of the city. The 44 km long line has 28 stations and the trip takes 65 minutes. 720,000 passengers use the urban rail lines on the European side of the city every day.

Trams first entered service in Istanbul on 3 September 1869, at the Tophane – Ortaköy line.^[118] In 1871 the Azapkapı – Galata; Aksaray – Yedikule; Aksaray – Topkapı; and Eminönü – Aksaray lines entered service.^[118] Other lines that entered service in the late 19th century included the Voyvoda Caddesi – Kabristan Sokağı – Tepebaşı – Taksim – Pangaltı – Şişli line; the Bayezid – Şehzadebaşı line; the Fatih – Edirnekapı – Galatasaray – Tünel line; and the Eminönü – Bahçekapı line.^[118] Since 1939 the trams of the city are operated by the İETT.^[118] On 12 August 1961, the historic red trams of Istanbul were removed from the city's European side; and on 14 November 1966, they were removed from the city's Asian side.^[118] Towards the end of 1990, replicas of these historic red trams were put in service along the İstiklal Avenue between Taksim and Tünel, which is a single 1.6 km-long (1640 m) line.^[118] On 1 November 2003, another nostalgic tram line (T3) was reopened on the Anatolian part of Istanbul between Kadıköy and Moda.^[119] It has 10 stations on a 2.6 km long route.^[119] The trip takes 21 minutes.^[119]

A fast tram (T1) was put in service in 1992 on standard gauge track with modern cars, connecting Sirkeci with Topkapı. The line was extended on one end from Topkapı to Zeytinburnu in March 1994, and on the other end from Sirkeci to Eminönü in April 1996. On 30 January 2005 it was extended from Eminönü to Fındıklı, crossing the Golden Horn through the Galata Bridge for the first time after 44 years. A final extension to Kabataş was opened in June 2006. The line has 24 stations on a length of 14 km. Service was initially operated with 22 LRT vehicles built by ABB, now reassigned to other lines; while stations were provided with temporary high platforms. These vehicles were replaced by 55 low-floor Bombardier Flexity Swift trams in 2003. An entire trip takes 42 minutes. The daily transport capacity is 155,000 passengers. The amount of investment totaled US$110 million. In September 2006, a second tram line (T2) was added, running west from Zeytinburnu to Bağcılar. Service on this line is operated with 14 ABB LRT cars. Stations have high platforms at the level of the car floor.

Istanbul is served by two underground funicular railways, of very different ages and styles. The older of these lines is the Tünel (1875). Inaugurated on 17 January 1875,^[120] the Tünel is the second-oldest subterranean urban rail line in the world after the London Underground (1863) (arguably third in the world, if one counts Brooklyn, New York's abandoned Atlantic Avenue Tunnel) and the first subterranean urban rail line in continental Europe; though the first full subway line with multiple underground stations in continental Europe was the Line 1 of the Budapest Metro (1896). The Tünel is 573 m (1,879.92 ft) long with an altitude difference of 60 m and no intermediate stations between Karaköy and Tünel Square.^[120] It has been continuously in service since 1875.^[120] Two trains run on a single rail every 3.5 minutes, and a trip takes 1.5 minutes.^[120] Making 64,800 trips, totaling 37,066 kilometres a year, the Tünel carries 15,000 passengers per day.

A second funicular line, the Kabataş-Taksim Funicular, entered service on 29 June 2006, connecting Kabataş and Taksim.^[121] This system connects the Seabus station and the tram stop in Kabataş to the metro station at Taksim Square.^[121] It is about 600 meters long and climbs approximately 60 meters in 110 seconds, carrying 9,000 passengers per day.

The Istanbul LRT is a light rail transit system consisting of 2 lines. The first line (M1) began service on 3 September 1989 between Aksaray and Kartaltepe. The line was further developed step-by-step and reached Atatürk Airport on 20 December 2002. The other line (T4) was opened in 2007 between Edirnekapı and Mescid-i Selam. There are 36 stations, including 12 underground and 3 viaduct stations, on the line's 32 km length. The lines are totally segregated from other traffic, without level crossings, and run underground for 10.4 km. Service is operated with LRT vehicles built by ABB in 1988.

Construction works of the Istanbul Metro (M2) began in 1992 and the first completed section between Taksim and 4. Levent entered service on 16 September 2000.^[122] This section of the line is 8.5 km (5.3 mi) long and has 6 stations.^[122] In 2000, there were 8 Alstom-built 4-car train sets in service, which ran every 5 minutes on average and transported 130,000 passengers daily. On 30 January 2009, the first train sets built by Eurotem entered service.^[123] Eurotem will build a total of 92 new wagons for the M2 line.^[123][124] As of 30 January 2009, a total of 34 train sets, each with 4 cars, were being used on the M2 line.^[124]

A northern extension from 4. Levent to Maslak was opened on 30 January 2009.^[125] The southern extension of the M2 line from Taksim to Yenikapı, across the Golden Horn on a bridge and underground through the historic peninsula, has thus far been completed up to the Şişhane station in Beyoğlu, which also entered service on 30 January 2009.^[125] At Yenikapı the M2 network will intersect with the extended light metro and suburban train lines, and with the Marmaray tunnel.

At present, the M2 line has 10 stations in service on the European side of the city; while 6 new stations on the European side and 16 new stations on the Asian side are currently under construction. The trip between the Şişhane station in Beyoğlu and the Atatürk Oto Sanayi station in Maslak is 15.65 km (9.7 mi) long and takes 21 minutes.^[126][127] The total length of the European side of the M2 line will reach 18.36 km (11.4 mi) when all 16 stations from Hacıosman to Yenikapı will be completed;^{[122][123][128]} not including the 936 metres long Golden Horn metro bridge,^[129] the 0.6 km long Taksim-Kabataş tunnel connection with the Seabus port,^[121] the 0.6 km long Yenikapı-Aksaray tunnel connection with the LRT network,^[123] and the 13.6 km long Marmaray tunnel.^[130]

On the Asian side, construction of the 21.66 km (13.5 mi) long M2 line from Kadıköy to Kartal continues, which will have a total of 16 stations.^[131] The Marmaray tunnel (Bosporus undersea railway tunnel) will connect the metro lines of the Asian and European parts of the city. According to the scheduled construction timeline, the tunnel will enter service in 2013.

Istanbul is becoming increasingly colourful in terms of its rich social, cultural, and commercial activities. While world famous pop stars fill stadiums, activities like opera, ballet and theatre continue throughout the year. During seasonal festivals, world famous orchestras, chorale ensembles, concerts and jazz legends can be found often playing to a full house. The Istanbul International Film Festival is one of the most important film festivals in Europe,^[132] while the Istanbul Biennial is another major event of fine arts.

Annually Istanbul hosts music and opera festivals. These festival are an outgrowth of Turkey's government policy starting in the early 1930s to introduce and instutionalize the teaching and performing of polyphonic music and opera. The policy was implemented using highly acclaimed musicologists, performers, composers, etc. who were at risk in their native Germany. Among them were Paul Hindemith, Licco Amar, Carl Ebert, and Ernst Praetorius. They are part of a music and opera directorate bound to the Ministry of Culture and Tourism.

Istanbul Modern frequently hosts the exhibitions of renowned Turkish and foreign artists. Pera Museum and Sakıp Sabancı Museum have hosted the exhibitions of world famous artists and are among the most important private museums in the city. The Doğançay Museum – Turkey’s first contemporary art museum – is dedicated almost exclusively to the work of its founder Burhan Doğançay. The Rahmi M. Koç Museum on the Golden Horn is an industrial museum that exhibits historic industrial equipment such as cars and locomotives from the 19th century and early 20th century, as well as boats, submarines, aircraft, and other similar vintage machines from past epochs.

Istanbul Archaeology Museum, established in 1881, is one of the largest museums of its kind in the world. The museum contains more than 1,000,000 archaeological pieces from the Mediterranean basin, the Balkans, Middle East, North Africa and Central Asia. Istanbul Mosaic Museum contains the late Roman and early Byzantine floor mosaics and wall ornaments of the Great Palace of Constantinople. The nearby Turkish and Islamic Arts Museum displays a vast collection of items from various Islamic civilisations. Sadberk Hanım Museum contains a wide variety of artifacts, dating from the earliest Anatolian civilisations to the Ottomans.^[133]

Occasionally, in November, the Silahhane (Armory Hall) of Yıldız Palace hosts the Istanbul Antiques Fair, which brings together rare pieces of antiques from the Orient and Occident.^[134] The multi-storey Mecidiyeköy Antikacılar Çarşısı^[135] (Mecidiyeköy Antiques Bazaar) in the Mecidiyeköy quarter of Şişli is the largest antiques market in the city, while the Çukurcuma neighbourhood of Beyoğlu has rows of antiques shops in its streets. The Grand Bazaar, edificed between 1455–1461 by the order of Sultan Mehmed the Conqueror also has numerous antiques shops, along with shops selling jewels, carpets and other items of art and artisanship. Historic and rare books are found in the Sahaflar Çarşısı near Beyazıt Square, and it is one of the oldest book markets in the world, and has continuously been active in the same location since the late Roman, Byzantine and Ottoman periods.

Live shows and concerts are hosted at a number of locations including historical sites such as the Hagia Irene, Rumeli Fortress, Yedikule Castle, the courtyard of Topkapı Palace, and Gülhane Park; as well as the Atatürk Cultural Center, Cemal Reşit Rey Concert Hall and other open air and modern theatre halls.

A significant culture has been developed around what is known as a Hamam, the Turkish word for a Turkish Bath. It was a culture of leisure during the Ottoman period, one of the finest example being the Çemberlitaş Hamamı (1584) in Istanbul, located on the Çemberlitaş (Column of Constantine) Square.^[136] Another fine example from the 17^th Century is the Galatasaray Hamamı, located on the Beyoğlu district, known for the quality of service and its cleanliness. In the Ottoman Empire, many Hamams were also actually build adjacent to mosques, as part of the "külliye" (complex). A very fine example to this is the Hamam of the Kılıç Ali Paşa Mosque built by Mimar Sinan.

Recently, old beaches have reopened in the city. The most popular places for swimming in the city are in Bakırköy, Küçükçekmece, Sarıyer and the Bosphorus. Outside the city are the Marmara Sea's Princes' Islands, Silivri and Tuzla; as well as Kilyos and Şile on the Black Sea.

The Princes' Islands (Adalar) are a group of islands where motor transportation is prohibited, located in the Marmara Sea, south of the Kartal and Pendik districts. Pine and stone-pine wooden neoclassical and art nouveau-style Ottoman era summer mansions from the 19th century and early 20th century, horse-drawn carriages and seafood restaurants make them a popular destination. They can be reached by commuter ferries or high-speed catamaran Seabus (Deniz otobüsü) from Eminönü and Bostancı. Of the nine islands, only five are settled.

Şile is a distant and well-known Turkish seaside resort on the Black Sea, 50 kilometres (31 mi) from Istanbul, where unspoiled white sand beaches can be found. Kilyos is a small calm seaside resort not far from the northern European entrance of the Bosphorus at the Black Sea. The place has good swimming possibilities and has become popular in the recent years among the inhabitants of Istanbul as a place for excursions. Kilyos offers a beach park with seafood restaurants and night clubs, being particularly active in the summer with many night parties and live concerts on the beach.

Istanbul has numerous historic shopping centers, such as the Grand Bazaar (1461), Mahmutpaşa Bazaar (1462) and the Egyptian Bazaar (1660). The first modern shopping mall in Turkey was Galleria Ataköy (1987), which was followed by dozens of others in the later decades, such as Akmerkez (1993), which is the only mall to win both "Europe's Best" and "World's Best" awards by the ICSC; Metrocity (2003); Cevahir Mall (2005), which is the largest mall in Europe; and Kanyon Mall (2006), which won the 2006 Cityscape Architectural Review Award for its interesting design. İstinye Park (2007) and City's Nişantaşı (2008) are two new malls that target high-end consumers and are almost exclusively dedicated to world-famous fashion brands.

Along with the traditional Turkish restaurants, many European and Far Eastern restaurants and numerous other cuisines are also thriving in the city. Most of the city's historic winehouses (meyhane in Turkish) and pubs are located in the areas around İstiklal Avenue in Beyoğlu. The 19th century Çiçek Pasajı (literally Flower Passage in Turkish, or Cité de Péra in French) on İstiklal Avenue, which has many historic meyhanes, pubs and restaurants, was built by Hristaki Zoğrafos Efendi at the former site of the Naum Theatre and was inaugurated in 1876. The famous Nevizâde Street, which has rows of historic meyhanes next to each other, is also in this area.

Other historic pubs are found in the areas around Tünel Pasajı and the nearby Asmalımescit Sokağı. Some historic neighbourhoods around İstiklal Avenue have recently been recreated, with differing levels of success; such as Cezayir Sokağı near Galatasaray Lisesi, that has rows of pubs, cafés and restaurants playing live music.^[137]

Istanbul is also famous for its historic seafood restaurants, as an example, Kumkapı has a pedestrian-only area that is dedicated to fish restaurants. Some 30 fish restaurants are found there, many of them among the best of the City. Also, many of the most popular seafood restaurants are found along the shores of the Bosphorus and by the Marmara Sea shore towards the south of the city.^[138][139] The largest of the Princes' Islands in the Sea of Marmara (namely Büyükada, Heybeliada, Burgazada and Kınalıada) and Anadolu Kavağı near the northern entrance of the Bosphorus towards the Black Sea (close to Yoros Castle, which was also known as the Genoese Castle due to Genoa's possession of it in the mid-15th century) also have many historic seafood restaurants.

There are many night clubs, pubs, restaurants and taverns with live music in the city. The night clubs, restaurants and bars increase in number and move to open air spaces in the summer. The areas around Istiklal Avenue, Nişantaşı, Bebek and Kadıköy offer all sorts of cafés, restaurants, pubs and clubs as well as art galleries, theaters and cinemas. Babylon^[140] and Nu Pera in Beyoğlu are popular night clubs both in the summer and in the winter.

The most popular open air summer time seaside night clubs are found on the Bosphorus, such as Sortie,^[141][142] Reina^[143][144] and Anjelique^[145] in the Ortaköy district. Q Jazz Bar in Ortaköy offers live jazz music in a stylish environment.

Venues such as Istanbul Arena in Maslak and Kuruçeşme Arena^[146] on the Bosphorus frequently host the live concerts of famous singers and bands from all corners of the world. Parkorman^[147] in Maslak hosted the Isle of MTV Party in 2002 and is a popular venue for live concerts and rave parties in the summer.

The first Turkish newspaper, Takvim-i Vekayi, was printed on 1 August 1831 in the Bâbıâli (Bâb-ı Âli, meaning The Sublime Porte) district. Bâbıâli became the main centre for print media. Istanbul is also the printing capital of Turkey with a wide variety of domestic and foreign periodicals expressing diverse views, and domestic newspapers are extremely competitive. Most nationwide newspapers are based in Istanbul, with simultaneous Ankara and İzmir editions.^[108] Major newspapers with their headquarters in Istanbul include Hürriyet, Milliyet, Sabah, Radikal, Cumhuriyet, Zaman, Türkiye, Akşam, Bugün, Star, Dünya, Tercüman, Güneş, Vatan, Posta, Takvim, Vakit, Yeni Şafak, Fanatik and Turkish Daily News. There are also numerous local and national TV and radio stations located in Istanbul, such as CNBC-e, CNN Türk, MTV Türkiye, Fox Türkiye, Fox Sports Türkiye, NTV, Samanyolu TV, Kanal D, ATV, Show TV, Star TV, Cine5, SKY Türk, TGRT Haber, Kanal 7, Kanal Türk, Flash TV and many others. In the city of Istanbul, there are over a hundred FM-radio stations.

During the Roman and Byzantine periods, the most important sporting events were the quadriga chariot races that were held at the Hippodrome of Constantinople, which had a capacity to accommodate more than 100,000 spectators.^[149] Today, sports like football, basketball and volleyball are very popular in the city. In addition to Beşiktaş, Galatasaray and Fenerbahçe, which field teams in multiple sports, several other clubs have also excelled in particular team sports; such as Efes Pilsen, Fenerbahçe Ülker, Galatasaray Cafe Crown and Beşiktaş Cola Turka in basketball; or Eczacıbaşı, Vakıfbank and Fenerbahçe in volleyball.

The Atatürk Olympic Stadium, the largest multi-purpose stadium in Turkey, is a 5-star UEFA stadium and a first-class venue for track and field; having reached the highest required standards set by the International Olympic Committee and sports federations such as the IAAF, FIFA and UEFA. The stadium hosted the 2005 UEFA Champions League Final. The Şükrü Saracoğlu Stadium, home of Fenerbahçe, which is also a 5-star UEFA stadium, hosted the 2009 UEFA Cup Final that went down to history as the last Final of the UEFA Cup football tournament. The UEFA Cup will be replaced by the UEFA Europa League starting from the 2009-2010 season.

The Sinan Erdem Dome, the largest multi-purpose indoor arena in Turkey, hosted the Final of the 2010 FIBA World Basketball Championship, and will also be the venue for the 2012 IAAF World Indoor Championships and the 2012 FINA Short Course World Championships. The Abdi İpekçi Arena hosted the Final of EuroBasket 2001, and was also the venue for the 1992 Euroleague Final Four.

Istanbul hosts several annual motorsports events, such as the Formula One Turkish Grand Prix, the MotoGP Grand Prix of Turkey, the FIA World Touring Car Championship, the GP2 and the Le Mans Series 1,000 km (621 mi) races at the Istanbul Park GP Racing Circuit. From time to time Istanbul also hosts the Turkish leg of the F1 Powerboat Racing on the Bosphorus. Several annual sailing and yacht races take place on the Bosphorus and the Sea of Marmara. The Golden Horn is where the rowing races take place. Major clubs like Galatasaray, Fenerbahçe and Beşiktaş, and major universities such as the Bosphorus University have rowing teams. Air racing is new to the city. On 29 July 2006, Istanbul hosted the 5th leg of the spectacular Red Bull Air Race World Series, as well as the 4th leg on 2 June 2007, in both cases above the Golden Horn.

Personal sports like golf, horse riding and tennis are gaining popularity as the city hosts international tournaments such as the WTA Istanbul Cup. For aerobics and bodybuilding, numerous fitness clubs are available. The Paintball sport has recently gained popularity and is practiced by two large clubs in the proximity of Istanbul. Martial arts and other Eastern disciplines and practices such as Aikido and Yoga can be exercised in several centers across the city. Istanbul also hosts the annual MTB races in the nearby Belgrad Forest and Büyükada Island. Two of the most prominent cycling teams of Turkey, namely the Scott/Marintek MTB Team and the Kron/Sektor Bikes/Efor Bisiklet MTB Team, are from Istanbul.