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.
Ecumenical Patriarch of Constantinople
The Council of Chalcedon in 451 established Constantinople as a patriarchate with ecclesiastical jurisdiction over Asia Minor (the dioceses of Asiane and Pontus) and Thrace as well as over the barbaric territories, non-converted lands outside the defined area of the Western Patriarchate (Old Rome) and the other three patriarchates, Alexandria, Antioch and Jerusalem, gave it appellate jurisdiction extraterritorially over canon law decisions by the other patriarchs and granted it honours equal to those belonging to the first Christian see, Rome, in terms of primacy, Rome retaining however its seniority (canon xxviii). Leo I refused to accept this canon, basing himself on the fact that it was made in the absence of his legates. In the 6th century, the official title became that of "Archbishop of Constantinople, New Rome, and Ecumenical Patriarch."