IstanbulIstanbul is the largest city in Turkey, constituting the country's economic, cultural, and historical heart. With a population of 14.1 million, the city forms one of the largest urban agglomerations in Europe, second largest in the Middle East and the third-largest city in the world by population within city limits. Istanbul's vast area of 5,343 square kilometres (2,063 sq mi) is coterminous with Istanbul Province, of which the city is the administrative capital. Istanbul is transcontinental, straddling the Bosporus—one of the world's busiest waterways—in north western Turkey, between the Sea of Marmora and the Black Sea. Its commercial and historical centre lies in Europe, while a third of its population lives in Asia.