Istanbul extends both on the European (Rumelia) and on the Asian (Anatolia) side of the Bosphorus and is thereby the only metropolis in the world which is on two continents.

Its 2000 Census population is 8,803,468 (city proper) and 10,018,735 (province), making it, by some counts, one of the largest cities in Europe.

The census bureau estimate for July 20, 2005 is 11,322,000 for Istanbul province, which is generally considered as the metropolitan area, making it one of the twenty largest metropolitan areas in the world.