Today the holder's seat is in the Church of St. George in the largest city in Turkey, though that church is a far cry from the old headquarters.
Some of the most famous men to hold this position include Photius in the 10th century and Michael Cerlularias, who oversaw the East-West Schism. Another holder was the golden-mouthed John Chrysostom, who is recognized as a saint by the Coptic Orthodox Church. Today the holder's seat is in the Church of St. George in the largest city in Turkey, though that church is a far cry from the old headquarters. For 10 points, identify this ecclesiastical position, held today by Bartholomew I and formerly seated in the Hagia Sophia, the leader of Eastern Orthodox Christianity.
Some of the most famous men to hold this position include Photius in the 10th century and Michael Cerlularias, who oversaw the East-West Schism.
{Patriarch} of {Constantinople} [prompt on partial answer]