Following the destruction of Athens by the Herulians in AD 267, the Acropolis was transformed into a fortress; its defenses were repaired and reinforced with outworks and additional gates that protected the Propylaia.

The official recognition of Christianity by Constantine the Great in AD 330 had little impact on Athens and the city, despite the empowerment of its Christian community, remained largely pagan.

Nevertheless, Christianity progressively took root and by the end of the 5th century AD many pagan temples had been converted into Christian churches. The Acropolis ceased to be the sacred sanctuary of the goddess Athena and was gradually transformed into a Christian shrine.