Constantinople
Constantinople (; ) was the capital city of the Roman/Byzantine Empire (330–1204 and 1261–1453), and also of the brief Crusader state known as the Latin Empire (1204–1261), until finally falling to the Ottoman Empire (1453–1923). It was reinaugurated in 324 from ancient Byzantium as the new capital of the Roman Empire by Emperor Constantine the Great, after whom it was named, and dedicated on 11 May 330. The city was located in what is now the European side and the core of modern Istanbul.
Roman emperor
The Tetrarchy ultimately degenerated into civil war, but the eventual victor, Constantine the Great, restored Diocletian's division of Empire into East and West. He kept the East for himself and founded his city of Constantinople as its new capital. Constantine's own dynasty was also soon swallowed up in civil war and court intrigue until it was replaced, briefly, by Julian the Apostate's general Jovian and then, more permanently, by Valentinian I and the dynasty he founded in 364. Though a soldier from a low middle-class background, Valentinian was made emperor by a conclave of senior generals and civil officials.