Interior of Hagia Sophia, Istanbul, Turkey, 19th century. View of carved wooden minbar and Islamic texts inside the building while it was a mosque. Built in the 6th century by the Byzantine Emperor Justinian, the Hagia Sophia (Aya Sofya) was intended to be the greatest church in Christendom. It remained the centre of the Byzantine Empire and the Eastern Orthodox Church until 1453 when Constantinople fell to the Ottoman Turks. It was then converted into a mosque, which it remained until secularised and turned into a museum by order of Kemal Ataturk in 1934.