Original name Byzantion, a Greek city founded in 667 BC. Became Constantinople when Constantine, one of the co-emperors of the Roman Empire, cut the ribbon on a new capital city for his part of the empire (the eastern part) in AD 330. It then served as the capital of the Eastern Roman Empire (also known as Byzantium) until the conquest by the Ottoman Turks in 1453. The modern Turkish republic changed the name to İstanbul in the 20th century.