Istanbul (Turkish: İstanbul), historically known as Byzantium and Constantinople is the largest city in Turkey and 3rd largest city proper in the world with a population of 13 million, also making it the largest metropolitan city proper in Europe and the second largest metropolitan area in Europe by population. Istanbul is also a megacity, as well as the cultural, economic, and financial centre of Turkey. The city covers 39 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. It extends both on the European (Thrace) and on the Asian (Anatolia) sides of the Bosphorus, and is thereby the only metropolis in the world that is situated on two continents. Istanbul is a designated alpha world city.
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. The historic areas of the city were added to the UNESCO World Heritage List in 1985.