English: Hagia Sophia built as the new Cathedral of Constantinople by the Emperor Justinian in 537 AD. In 1453, the Ottoman Sultan Mehmet the Conqueror converted the Great Church into his mosque. Instanbul, Turkey Today, use of the complex as a place of worship (mosque or church) is strictly prohibited. However, in 2006, it was reported that the Turkish government allowed the allocation of a small room in the museum complex to be used as a prayer room for Christian and Muslim museum staff.