Which city was the capital of the Byzantine Empire and is now called Istanbul?

Constantinople was the capital of the Byzantine Empire and is now called Istanbul.

Roman Emperor Constantine the Great dedicated the city as Constantinople in 330 CE after expanding the older Greek city of Byzantium. Its position beside the Bosporus gave it control of a major route between Europe and Asia and between the Black Sea and the Mediterranean.

Constantinople became the political, religious, and economic center of the Eastern Roman Empire, commonly called the Byzantine Empire by modern historians. Its landmarks included the Hagia Sophia, the Hippodrome, and massive land walls. The city survived repeated sieges for centuries.

Ottoman Sultan Mehmed II conquered Constantinople on 29 May 1453, ending the Byzantine Empire. The city remained a major Ottoman capital. “Istanbul” developed from a Greek phrase meaning “to the city” and became the official English name used for the city in the 20th century.