Istanbul (Turkish: Istanbul; historically Byzantium and
Constantinople; see the other names of Istanbul) is the
largest city in Turkey, largest city proper and second
largest metropolitan area in Europe, and fifth largest
city proper in the world with a population of 12.6 million.
Istanbul is also a megacity, as well as the cultural
and financial centre of Turkey. The city covers 27 districts
of the Istanbul province. It is located on the Bosphorus
Strait and encompasses the natural harbour known as the
Golden Horn, in the northwest of the country.