At the Greek Orthodox Patriarchate. The church is dedicated to St. George. A group of visitors attended a service and then had their pictures taken by the priests.

A viewer supplied further information: The Patriarchal Cathedral: Since Byzantium the Cathedral of the Ecumenical Patriarchate due to political changes and persecutions have changed many churches. It started with St. Irene next to Aya Sofya (169-360) then when Aya Sofya was built as the "Great Church of Christ" moved to AyaSofya in (360) and stayed there until May29,1453.
On January 1453 moved to the church of 12 Disciples, which was built by Konstantine the Great, burial ground of Emperors and Patriarchs and stayed there until 1455. ( Today, Fatih Camii) (built between 1463-1470 by the Greek Architect Christodoulos).
The Patriarchal Cathedral moved to the Monastery of Pammakaristos (1455-1587) (today, Fethiye Camii).
The Cathedral moved to the church of Lady of Paramythia and stayed there until 1597. (1587-1597).
The Cathedral and the Patriarchate in full poverty moved to St. Demetrios of Xyloportas (woodendoor) (1597-1599) and in 1599 moved to the present location of Saint George Cathedral. The church at the present location was a small church for nuns and for the parishioners living around. Literally in the "Castle of Petrios", the Phanar Gate. (Diplofanaro=doubleLamp). Patriarch Timothy enlarged it and later Patriarch Jeremias II (1716-1726) built a completely new and large church. During the Patriarchy of Demetrios (1974-1991) the offices were rebuilt(1989) and during the Patriarchy of the present Patriarch Bartholomeos( 1991-today) the Cathedral was renovated all by Aggelopoulos Family generous donation.