Istanbul was founded by Byzantion.
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 . Founded under the name of Byzantion on the Sarayburnu promontory around 660 BCE , the city developed to become one of the most significant in history .