Constantinople Founded in 330 AD—Now Istanbul

Roman Emperor Constantine the Great officially dedicated Constantinople as his new capital on May 11, 330 AD. Built on the site of ancient Byzantium, it commanded the Bosphorus Strait, linking Europe and Asia. For over 1,600 years it served as the capital of the Eastern Roman (Byzantine) Empire, then the Ottoman Empire. In 1930, the Turkish Republic officially renamed it Istanbul—today a megacity of 15+ million, Turkey's cultural and economic heart, straddling two continents.