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.
Battle of Chrysopolis
A year later, Constantine's nephew the younger Licinius also fell victim to the emperor's anger or suspicions. In defeating his last foe, Licinius, Constantine became the sole emperor of the Roman empire; the first such since the elevation of Maximian to the status of augustus by Diocletian in April 286. After his conquest of the eastern portion of the Roman Empire Constantine made the momentous decision to give the east its own capital, and the empire as a whole its second. He chose the city of Byzantium — renamed "Constantinopolis" — as the site of this new foundation.Primary sources