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 line of Roman emperors in the Eastern Roman Empire continued unbroken at Constantinople until the capture of Constantinople in 1204 by the Fourth Crusade. In the wake of this action, four lines of Emperors emerged, each claiming to be the legal successor: the Empire of Thessalonica, evolving from the Despotate of Epirus, which was reduced to impotence when its founder Theodore Komnenos Doukas was defeated, captured and blinded by the Bulgarian Emperor Ivan Asen III; the Latin Empire, which came to an end when the Empire of Nicaea recovered Constantinople in 1261; the Empire of Trebizond, whose importance declined over the 13th century, and whose claims were simply ignored; and the Empire of Nicaea, whose claims based on kinship with the previous emperors, control of the Patriarch of Constantinople, and possession of Constantinople through military prowess, prevailed. The successors of the emperors of Nicaea continued until the fall of Constantinople in 1453 under Constantine XI Palaiologos.