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.
Istanbul
The Ottomans quickly transformed the city from a bastion of Christianity to a symbol of Islamic culture. Religious foundations were established to fund the construction of ornate imperial mosques, often adjoined by schools, hospitals, and public baths. The Ottoman Dynasty claimed the status of caliphate in 1517, with Constantinople remaining the capital of this last caliphate for four centuries. Suleiman the Magnificent's reign from 1520 to 1566 was a period of especially great artistic and architectural achievement; chief architect Mimar Sinan designed several iconic buildings in the city, while Ottoman arts of ceramics, stained glass, calligraphy, and miniature flourished. The population of Constantinople was 570,000 by the end of the 18th century.