The city that was the capital of the Byzantine Empire before it fell to the Ottomans in 1453 is Constantinople. Originally founded as Byzantium, it was renamed Constantinople in 330 CE by Emperor Constantine the Great. The city became a major center of trade, culture, and Christianity, and it was famed for its architectural wonders, including the Hagia Sophia. Constantinople's strategic location made it a vital hub connecting Europe and Asia. The fall of the city to the Ottomans, led by Sultan Mehmed II, marked the end of the Byzantine Empire and is viewed as a significant turning point in world history.