The ancient city that served as the capital of the Byzantine Empire was Constantinople. Founded by the Roman Emperor Constantine the Great in 330 CE, the city became a vital center for trade, culture, and religion, and was strategically located between Europe and Asia. Renamed from Byzantium to Constantinople, it was characterized by its impressive architecture, including the Hagia Sophia, and significant administrative and military structures. Its prominence continued until the Ottoman conquest in 1453, marking the end of the Byzantine Empire and the rise of Ottoman power.