Istanbul has a long history as a settlement dating back to 3000 BC. In the 7th century BC, Greek settlers founded the city of Byzantium at the site, naming it after their leader Byzas. Constantine the Great made Byzantium the capital of the Eastern Roman Empire in AD 306 and renamed it Constantinople. The city grew to become a major cultural and economic center but was weakened by repeated attacks over centuries. In 1453, the Ottoman Turks conquered Constantinople under Mehmet II and renamed it Istanbul, establishing it as the capital of the Ottoman Empire. Istanbul remains a thriving metropolis today with over 13.6 million residents across its European and Asian sides.