Hagia Irene is the oldest church in Istanbul. Emperor Constantine dedicated it to the Holy Peace of God in the 4th century.
The first Council of Constantinople was held here where the third part of the creed professing the faith in the divinity of the Holy Spirit was proclaimed.
The words of the creed: I believe in the Holy Spirit. …..continued to be present to my mind as I reconstructed the lively debate that these walls witnessed in hammering out the orthodox doctrine of the Catholic faith.
At the time of the conquest in 1453 Mehmet turned it into an armoury.