The St. Irene (Haghia Eirene, Greek: Ἁγία Εἰρήνη, Holy Peace or Divine Peace, commonly rendered incorrectly in English as St. Irene) church, the church of the divine peace. It was one of the first churches in the old Byzantium, and has been rebuilt by Constantine the Great or his son Constantinus. It was the cathedral of the patriarch until the Haghia Sophia was finished. After that church had been destroyed in 404 it became the cathedral for another ten years.
It is located within the walls around the Topkapı palace. But it being a museum in its own right I put it in a gallery of its own.