Hagia Sophia, was an early Christian church  and later an Eastern Orthodox church. It was built in 537 where two earlier churches had burned down. After an earthquake Trdat the Architect finished rebuilding it again in 994. Ottoman rulers made into a mosque in 1453.  It became a museum in 1935. It is in Istanbul, Turkey. Hagia Sophia is often said to be one of the greatest, and most beautiful buildings in history.