The Acropolis is surrounded by a Hellenistic wall contemporary with the Propylaea and the stairway leading to the entrance to the site. It is a carefully built ashlar construction with vertical and horizontal joints. A wall protected the Acropolis after the time of the Persian War. A Roman inscription mentions that the wall and square towers were repaired at the expense of P. Aelius Hagetor, the priest of Athena (2nd c. AD).