Istanbul is currently Constantinople.
Constantinople ( Κωνσταντινούπολις Konstantinoúpolis or Κωνσταντινούπολη Konstantinoúpoli Constantinopolis قسطنطینية , Ḳosṭanṭīnīye ) was the capital city of the Roman/Byzantine ( 330 -- 1204 and 1261 -- 1453 ) , and also of the brief Latin ( 1204 -- 1261 ) , and the later Ottoman ( 1453 -- 1923 ) empires . Istanbul ( [ ˌɪstænˈbʊl ] , [ - ˈbuːl ] or [ - stɑːn - ] İstanbul [ isˈtɑnbuɫ ] ) , historically known as Constantinople and Byzantium , is the most populous city in Turkey and the country 's economic , cultural , and historic center .