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.
Episcopal polity
Shortly after the Roman Emperor Constantine I legalized Christianity in 321, he also constructed an elaborate second capital of the Roman Empire located at Byzantium and renamed it Constantinople, in 324. The single Roman Empire was divided between these two autonomous administrative centers, Roman and Constantinopolitan, West and East, Latin speaking and Greek speaking. This remained the status quo through the fourth century. A deep chasm developed between the East and West, becoming critical around 350, known as the Arian, or Nicene controversy. The Eastern Christian Churches were thought by Constantine to believe against the Trinity; that Christ was lesser than God. Hilary, Bishop of Poitiers, France, believed that the Eastern Church should be given the opportunity to, at least, be educated on the subject. Constantine, in his wisdom, and upset by disagreement, banished Hilary to the East. Hilary perfected his Greek language skills while in exile, and determined the great divide between Rome and the East was actually not a disagreement at all, and was merely a linguistic ignorance on the part of his Latin speaking contemporaries. This truth became known in the West, though some differences lingered. Hilary of Poitiers later became St. Hilary, Doctor of the Church, for exposing the true Christian beliefs of the Eastern Church. Many of Hilary's writings were lost to time.