What is the name of the capital of the Byzantine Empire?

The story behind the answer

Founded by Emperor Constantine I in 330 CE on the site of Byzantium, Constantinople became the imperial seat of the Eastern Roman (Byzantine) Empire and remained its capital until its fall in 1453. Rome was the center of the earlier, western empire; Thessalonica was an important provincial hub but not the capital; Ankara is the modern capital of Turkey, centuries later.

Its strategic perch on the Bosporus let it control trade between the Black Sea and the Mediterranean, making it fabulously wealthy and defensible, with the Theodosian Walls and the masterpiece Hagia Sophia. As a bridge between Greco-Roman traditions and Christian Orthodoxy, it preserved classical learning for centuries. Its conquest by Mehmed II marked a turning point in world history.