 St. George's Cathedral, Istanbul

The Church of St. George (; ) is the principal Eastern Orthodox cathedral still in use in Istanbul, the largest city in Turkey and, as Constantinople, capital of the Byzantine Empire until 1453.Since about 1600, it has been the seat of the Ecumenical Patriarchate of Constantinople whose leader is regarded as the "primus inter pares" (first among equals) in the Eastern Orthodox Church, and as the spiritual leader of 300 million Orthodox Christians worldwide.