Istanbul

Istanbul ( ISS-tan-BUUL, also US: ISS-tan-buul; Turkish: İstanbul [isˈtanbuɫ] ), formerly known as Byzantium and Constantinople, is the most populous city in Turkey and the country's economic, cultural and historic center. Istanbul is a transcontinental city in Eurasia, straddling the Bosporus strait (which separates Europe and Asia) between the Sea of Marmara and the Black Sea. Its commercial and historical center lies on the European side and about a third of its population lives in suburbs on the Asian side of the Bosporus. With a total population of around fifteen million residents in its metropolitan area, Istanbul is one of the world's largest cities by population, ranking as the world's fifteenth-largest city and the largest city in Europe. The city is the administrative centre of the Istanbul Metropolitan Municipality (coterminous with Istanbul Province).
Founded under the name of Byzantion (Βυζάντιον) on the site of an earlier Thracian settlement around 660 BCE, the city grew in size and influence, becoming one of the most important cities in history. After its reestablishment as Constantinople in 330 CE, it served as an imperial capital for almost sixteen centuries, during the Roman/Byzantine (330–1204), Latin (1204–1261), Byzantine (1261–1453) and Ottoman (1453–1922) empires. It was instrumental in the advancement of Christianity during Roman and Byzantine times, before the Ottomans conquered the city in 1453 CE and transformed it into an Islamic stronghold and the seat of the Ottoman Caliphate. Under the name Constantinople it was the Ottoman capital until 1923. The capital was then moved to Ankara and the city was renamed Istanbul.