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.
Architecture of Istanbul
The most important monuments of Roman architecture in the city include the Column of Constantine (), which was erected in 330 by Constantine the Great for marking the declaration of the new capital city of the Roman Empire and contained several fragments of the True Cross and other artifacts belonging to Jesus Christ and Virgin Mary, the "Mazulkemer Aqueduct", the Valens Aqueduct, the Column of the Goths in Gülhane Park, the Milion which served for calculating the distances between Constantinople and other cities of the Roman Empire, and the Hippodrome of Constantinople which was built following the model of the Circus Maximus in Rome.