Virgin Mary Athiniotissa, Medieval church building near Acropolis, Athens, Greece

Panagia Atheniotissa was the Christian church installed inside the Parthenon on the Acropolis of Athens. The temple's naos became the nave and the opisthodomos the narthex, entered from the west through a single doorway cut in a low wall closing the pronaos columns. The east pronaos was walled off into a semicircular apse, with a marble throne for the bishop at its centre, and a baptistry was screened off in the narthex.

The Parthenon's conversion into a church likely happened before 578–582, when Christian tombs with datable coins appeared on its south side; Justinian I consecrated it as the "catholic church of Athens". A late Roman fire had destroyed the original roof, so only the naos was re-roofed while the colonnade stood open to the sky. In 1206 a papal bull made it the Catholic cathedral of Our Lady; it returned briefly to Orthodox use in 1458 and became a mosque after 1460.

The church was known as the "Catholic Church of Athens" after Justinian I consecrated it, and a 15th-century manuscript credits its construction to Apollonius and Eulogius. A golden icon of the Virgin hung in a niche above the altar, and an ever-burning lamp, mentioned by Pausanias, kept burning there.

The church occupied the Parthenon on the Acropolis rock, entered from the west through a single doorway cut into a low wall between the pronaos columns. Inside, the old opisthodomos served as narthex, with a screened baptistry and two side doors added on the north and south walls. The naos became the nave, ending in a semicircular apse built into the walled-off east pronaos.

Some 232 Christian-era graffiti survive on the Parthenon's walls, 60 of them datable, and they record worship in the church. Parts of the ancient frieze were cut away to make clerestory windows for the nave and to form the apse, while many sculpted figures were deliberately defaced; the metopes suffered most.