Christianity in Turkey
Constantinople became established in the ecclesiastical hierarchy at the Council of Constantinople in 381. Second only to Rome, the legendary origins of the Patriarchate of Constantinople go back to St. Andrew, Metrophanes and Alexander of Constantinople. Constantinople's primacy over the Patriarchates of Alexandria and Antioch was reaffirmed at the Council of Chalcedon in 481, after which the papacy in Rome supported Constantinople in its dispute with Alexandria over monophysitism. Later, when Rome sought to assert its primacy over Byzantium, the Eastern Orthodox church developed the doctrine of pentarchy as a response.
İzmit
Nicomedia remained as the eastern (and most senior) capital of the Roman Empire until Licinius was defeated by Constantine the Great in 324. Constantine mainly resided in Nicomedia as his interim capital city for the next six years; until in 330 he declared the nearby Byzantium as "Nova Roma", which eventually became known as Constantinople. Constantine died in a royal villa at the vicinity of Nicomedia in 337. Owing to its position at the convergence of the Asiatic roads leading to the new capital, Nicomedia retained its importance even after the foundation of Constantinople.