What structure did the Parthenon serve as in the 5th century AD?

The Parthenon served as a Christian church in the 5th century AD.

After centuries as a temple dedicated to Athena, the building was converted into a church in the final decades of the 5th century. It was associated with the Virgin Mary and became known as the Church of the Parthenos Maria or the Church of the Theotokos. The conversion followed the decline and suppression of pagan cults in the late Roman Empire.

The transformation altered the building substantially. Its liturgical orientation was changed, an apse was built at the eastern end, and the cella became the church’s nave. A large portal connected the former inner chambers, while Christian paintings and inscriptions were added. Some pagan sculptures were removed or damaged.

A common mix-up is to associate the Parthenon’s Christian phase with the later Ottoman period, when it became a mosque. It remained a Christian church for roughly a millennium before that later conversion.