Istanbul is a human settlement.
A city is a large and permanent human settlement . The city today known as Istanbul has been the site of human settlement for approximately three thousand years . 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 . The city is the administrative center of the Istanbul Metropolitan Municipality ( conterminous with Istanbul Province ) , both hosting a population of around 14.7 million residents . Istanbul is one of the world 's most populous cities and ranks as the world 's 7th-largest city proper and the largest European city .