St. Irene, which is located on 1st courtyard of Topkapi Palace, was constructed by the Emperor Lustiniaus in VI. century. It consists of atrium, narthex, naos with three nephs and apse. It is a typical Byzantine structure with its material and architecture. There have not been many changes in the building, as the church was not turned to a mosque after conquest of istanbul in 1453. It was used as a booty and weapon warehouse for a long time.