History: The Byzantine basilica Hagia Sion was built under John II, Bishop of Jerusalem in the early 5th century, A monastic order known as the Abbey of Our Lady of Mount Zion was established at the site in the 12th century, with a church built on the ruins of the earlier Byzantine church.
Importance: it is one of the three earliest churches in Jerusalem, stood on this site. Built by the Emperor Constantine, it was regarded as the Mother of all Churches.
Location: The church is located on mount Zion just beyond the walls of Old Jerusalem. It is located near the Zion gate.