Istanbul, Turkey, known before 330 as Byzantium and between 330 and 1930 as Constantinople, is a transcontinental city of Europe and Asia, straddling the Bosporus strait between the Sea of Marmara and the Black Sea. Its commercial and historical center lies on the European side; about a third of its residents live on the Asian side. The population of the city has increased tenfold since the 1950s to around 15 million, making Istanbul one of the world's most populous cities and the fourth-largest city proper. Founded on the Sarayburnu promontory around 660 BCE, the city grew in size and influence. It was an imperial capital for almost 16 centuries, during the Roman and Byzantine (330–1204), Latin (1204–1261), Palaiologos Byzantine (1261–1453) and Ottoman (1453–1922) empires. Although Ankara was chosen as the new capital after the Turkish War of Independence, Istanbul remains Turkey's economic and cultural center.