Constantinople (Greek: Κωνσταντινούπολις, Κωνσταντινούπολη – Konstantinoúpolis, Konstantinoúpoli; Latin: Constantinopolis; Ottoman Turkish: قسطنطینیه, Kostantiniyye; and modern Turkish: İstanbul) was the capital city of the Eastern Roman or Byzantine Empire, the Latin and the Ottoman Empire. It was founded in AD 330, at ancient Byzantium as the new capital of the Roman Empire by Constantine the Great, after whom it was named. In the 12th century, the city was the largest and wealthiest European city.

Eventually the empire of Christian Eastern Orthodoxy in the east was reduced to just the capital and its environs, falling to the Ottomans in the historic battle of 1453.

The city itself remained and prospered as the Muslim capital in the Ottoman period; however, scholars normally reserve the name "Constantinople" for the city in Christian period 330–1453, preferring "Istanbul" for the city's name in later centuries. However, many Western writers have continued to refer to the city by its older name "Constantinople" into modern times. The name "Constantinople" is still used by members of the Eastern Orthodox Church in the title of one of their most important leaders, the Orthodox patriarch based in the city, referred to as "His Most Divine All-Holiness the Archbishop of Constantinople New Rome and Ecumenical Patriarch."