Istanbul is located on the historic Silk Road in modern day Turkey.
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 . Istanbul 's strategic position on the historic Silk Road , rail networks to Europe and the Middle East , and the only sea route between the Black Sea and the Mediterranean have produced a cosmopolitan populace , although less so since the establishment of the Turkish Republic in 1923 .