For almost a millennium after its construction, it was the largest cathedral in all of Christendom. It served as a center of religious, political, and artistic life for the Byzantine world and has provided us with many useful scholarly insights into the period.Hagia Sophia, also called Church of the Holy Wisdom or Church of the Divine Wisdom, an important Byzantine structure in Istanbul and one of the world’s great monuments. It was built as a Christian church in the 6th century ce(532–537) under the direction of the Byzantine emperor Justinian I. In subsequent centuries it became a mosque, a museum, and a mosque again. The building reflects the religious changes that have played out in the region over the centuries, with the minarets and inscriptions of Islam as well as the lavish mosaics of Christianity.