<human>:  When was the Hagia Sophia (znik) built?
<bot>: The Hagia Sophia was built in the 6th century. It was originally a church dedicated to the Virgin Mary, but later became a mosque. In the 15th century, the Ottomans conquered Constantinople, and the Hagia Sophia became a mosque again. In 1935, the Hagia Sophia was converted into a museum.