Istanbul (pop. 6,620,200), city in northwest Turkey, lying on the Sea of Marmara and divided by the Bosporus (strait). Until 1930 its official name was Constantinople, of which Istanbul was originally a contraction. Built in A.D. 330 on the site of a former Greek town, Byzantium, it reached its cultural height under Justinian I in the 6th century. After years of decay it was taken by the Ottoman Turks in 1453, and was rebuilt as the Turkish capital, which it remained until 1923 when the capital was moved to Ankara. It is still the economic and cultural heart of Turkey, a port, transport hub, and manufacturing center.
See also: Turkey.