The capital of the ancient Roman Empire before it moved to Constantinople was Rome itself. Rome served as the political and cultural heart of the empire for centuries, known for its architectural, legal, and military achievements. The city was a hub for governance, commerce, and social life, and it held immense importance in the Roman framework. In 330 AD, Emperor Constantine the Great moved the capital to Byzantium, renaming it Constantinople, to better position the empire's center of power closer to the eastern provinces and to protect against threats from various groups.