Claim: Istanbul is a world center.
Evidence: Istanbul -LRB- -LSB- ˌɪstænˈbʊl -RSB- , -LSB- - ˈbuːl -RSB- or -LSB- - stɑːn - -RSB- İstanbul -LSB- isˈtɑnbuɫ -RSB- -RRB- , historically known as Constantinople and Byzantium , is the most populous city in Turkey and the country 's economic , cultural , and historic center.