The Church of Agia Sofia is one of the oldest churches in Thessaloniki - in its place, there used to stand a small church as early as in the 3rd century, and in the 8th century a church in its current form was built - with the cathedral of Hagia Sophia in Constantinople as a model. In 1205 when Thessaloniki was conquered during the Fourth Crusade, the church was transformed into a cathedral which it remained even after 1246 when Thessaloniki was returned to the Byzantine Empire. After the sultan Murad II conquered Thessaloniki in 1430, the Church of Agia Sofia was rebuilt to become a mosque.

The church is a vaulted basilica with a plan in the shape of the Greek, i.e. equilateral cross, being one of most representative edifices of this kind of architecture.  During the iconoclast era, it was decorated by gold mosaics and a large golden cross that was replaced by a picture of Mary (Theotokos) during 787-797 AD after the triumph of iconolators. The current mosaic in the apsis represents the ascension of the Christ with a writing ‘Ye men of Galilee, why stand ye gazing up into heaven?’ (Acts 1.11.). On the vault, the twelve apostles, Virgin Mary and two angels and depicted.

Agia Sofia is a part of the UNESCO World Heritage.