Istanbul

Istanbul is a very big city in Türkiye.

A long, narrow sea called the Bosporus flows through the middle. Part of the city is in Europe, and part is in Asia. Boats zoom back and forth all day.

Istanbul is the largest city and busiest port in Türkiye, though it is not the capital; that is Ankara. About 15.7 million people lived in Istanbul province in 2023. The city sits on both sides of the Bosporus, a narrow strait that joins the Black Sea to the Sea of Marmara and divides Europe from Asia.

The oldest part of the city stands on a triangle of land in Europe with seven hills. For more than 2,500 years, armies, traders and travelers have passed through here, and the city has had three famous names: Byzantium, Constantinople and Istanbul.

Istanbul is Türkiye's largest city and principal seaport, and the capital in turn of the Byzantine and Ottoman empires. The old walled city stands on a triangular peninsula of about 23 km², with seven hills, six of them crests of a ridge above the Golden Horn; around their slopes stand the mosques and monuments UNESCO inscribed as the Historic Areas of Istanbul in 1985. The modern municipality spreads far beyond, on both the European and Asian shores, and Istanbul province counted 15,655,924 people in 2023.

The name has changed with its rulers. Greek Byzantium was renamed by Constantine, who dedicated it as his capital in 330 CE; the name Constantinople lasted until the Turkish Post Office officially changed it in 1930. The name Istanbul grew over centuries from a Greek phrase, eis tēn polin, "into the City", which travelers used for trips there. Britannica notes that for more than 2,500 years the city has stood, sometimes as a bridge and sometimes as a barrier, between surges of religion, culture and imperial power.

Istanbul has many famous buildings.

Hagia Sophia has a giant dome and tall towers called minarets. The Blue Mosque has six minarets. Topkapı Palace was home to sultans. Under the ground is a huge old water tank with hundreds of stone columns.

Hagia Sophia was built as a church from 532 to 537 for the emperor Justinian. Its dome is 32 meters across. In 1453 it became a mosque, from 1935 to 2020 it was a museum, and since 2020 it has been a mosque again. Nearby stands the mosque of Sultan Ahmed I, often called the Blue Mosque, which has six minarets instead of the usual four.

Topkapı Palace, begun in 1462, was home to the Ottoman sultans for centuries. Under the streets, the Basilica Cistern stored water on 336 columns. The Grand Bazaar once held 4,000 shops, and the Aqueduct of Valens, built in 366, still crosses a valley in the old city.

Hagia Sophia, the largest of the city's 25 surviving Byzantine churches, is essentially Justinian's 6th-century building, rebuilt after the Nika riot of 532; its dome, 32 m across, fell in an earthquake in 559 and was rebuilt to a smaller scale. It became a mosque in 1453, a museum from 1935 to 2020, and a mosque again in 2020. The great Ottoman mosques of the mid-15th to mid-16th centuries crown the seven hills; Mimar Koca Sinan's masterpiece, the Süleymaniye Mosque (1550–57), was inspired by Hagia Sophia, and the mosque of Ahmed I, the Blue Mosque, has six minarets.

Topkapı Palace, begun by Mehmed II in 1462, was the sultans' residence until the early 19th century; its courts hold the treasury and collections of manuscripts, china and textiles. Byzantine engineering survives in the two-story Aqueduct of Valens (366) and more than 80 closed cisterns, above all the Basilica Cistern with its 336 columns. The land walls, a double line built in 413 and 447 and 7 km long, were breached only once, in 1453.

In Istanbul, boats are like buses on the water.

Ferries carry people from Europe to Asia and back. Big bridges cross the water. A train even goes under the sea in a tunnel!

Because water runs through the middle of Istanbul, ferries are part of everyday life. They carry commuters across the Bosporus between Europe and Asia, and some sail south to the Princes' Islands. Buses run on the streets, and different kinds of trains run through the center.

The Bosphorus Bridge, about 1.6 kilometers long, opened in 1973. The Marmaray rail line goes through a tunnel under the Bosporus, so trains can travel from Europe to Asia under the sea. Istanbul Airport, about 50 kilometers northwest of the center, connects the city with the world.

Britannica lists the city's transport as rail lines of several kinds in the center, buses for internal transport, and maritime services from harbor dinghies and small ferries to international liners; ferries range as far as the Princes' Islands (Kızıl Adalar) to the south. The Marmaray line links the European and Asian sides through a tunnel beneath the Bosporus, and Istanbul Airport, about 50 km northwest of the center, handles international and domestic flights.

The Bosphorus Bridge, a suspension bridge about 1,560 m long, opened on October 30, 1973 (Wikidata). Crossing the water has a long history: the first bridge across the Golden Horn was built in 1838, and steamships began bringing European visitors in the 1830s. Today the city is governed through 39 district municipalities, 27 in the city itself and 12 outside it, within a metropolitan municipality.

Istanbul has warm summers and cool, rainy winters.

Strong winds blow from the seas. Sometimes a very cold wind blows in winter. In summer, the sun shines and the sea sparkles.

Istanbul has warm, fairly dry summers and cool, wet winters. Türkiye's weather service gives an average of 6.8 °C in January and 24.7 °C in July and August. About 660 millimeters of rain fall in a year, most of it in late autumn and winter; December is the wettest month and July the driest.

Winds shape the weather. The poyraz blows from the Black Sea in the northeast. In winter an icy wind from the Balkans, the karayel, can bring hard frosts, and the lodos from the southwest can whip up storms on the Sea of Marmara.

Turkish State Meteorological Service averages for 1950–2025 give monthly means from 6.8 °C in January (6.9 °C in February) to 24.7 °C in July and August, with average highs near 29.7 °C in midsummer. Monthly precipitation ranges from 22.1 mm in July to 99.2 mm in December, about 660 mm a year in total, so most falls between October and March.

Britannica describes the winds: the prevailing northeasterly poyraz off the Black Sea; in winter the karayel, an icy blast from the Balkans capable of freezing the Golden Horn and even the Bosporus; and the lodos from the southwest, which raises storms on the Marmara. The water itself is layered: the colder, less salty Black Sea flows south through the Bosporus on the surface, while warmer, saltier Mediterranean water pushes north beneath it as a strong undercurrent.

Istanbul is busy day and night.

People ride ferries to work and school. They shop in markets and bazaars. Families walk by the water and watch the ships go by.

Istanbul grew enormously in the 1900s as people moved in from the countryside to find work. Today old wooden houses on narrow lanes stand near modern skyscrapers, offices and shopping malls. Ships of every size, from tiny boats to big ferries, crowd the Bosporus.

The city has more than 400 fountains, many built as gifts to the public, and many museums, including the Archaeological Museums of Istanbul and the Museum of Turkish and Islamic Art. In the Grand Bazaar, with its grid of covered streets, shoppers still bargain as they have for centuries.

Britannica describes a city where unpaved alleys with old wooden houses coexist with high-rise buildings, office parks and shopping malls, and where wide roads now cut through the historic quarters. A nearly tenfold rise in population in the second half of the 20th century strained housing and services, and early in the 21st century foreign investment drove rapid renewal, restorations and new skyscrapers, along with debate over protecting the city's heritage and green space.

Cultural institutions include the Archaeological Museums of Istanbul, the Museum of Turkish and Islamic Art, and the Köprülü Library (1677), with early Ottoman printed books and manuscripts more than 1,000 years old. The city has more than 400 fountains, the grandest built by Ahmed III in 1728 behind Hagia Sophia. Istanbul is also a religious center: since 381 it has been the seat of the patriarch of Constantinople, who remains first among equals among the leaders of the Eastern Orthodox Church.