One of the most significant monuments of the ancient city of Aigeira is its ancient theater. It has a horseshoe-shaped concave overlooking the Corinthian Gulf and is located at an altitude of 350 m above sea level, north of the ancient acropolis. Its construction probably dates back to the first half of the 3rd c. BC, around 280-250 BC, when probably the second Common of the Achaeans was founded - the Achaean Confederation - and the Achaean cities were reorganized.