The prehistoric citadel of Teichos Dymaion, also known as ?Kastro tis Kalogrias? (the castle of Kalogria) occupies an imposing rocky hilltop at the southernmost tip of the so-called ?Mavra Vouna? (black mountains), a few hundred meters from the village of Araxos. This is the only fortified mycenaean acropolis in western Greece.

The site has been identified with Teichos Dymaion by Polybius and Strabo and the name has been confirmed by the finding of roof tile fragments bearing the stamp of neighboring Dyme, the dominant ancient city of the region. The name Teichos Dymaion dates back to the hellenistic period, when the mycenaean fort was the stronghold of Dyme in its defense against the raids of the Eleians and the Aitolians. An older name could have been Larissa (a common name, used for fortified citadels), mentioned by ancient writers as lying near river Larissos.

The location offers obvious strategic advantages to its inhabitants, providing unhindered views to the surrounding plain - the Dymaian land - and to the coastal zone towards the gulf of Patra to the north and the Ionian sea to the west.

This strategic location, along with the ample natural resources of the region, the Prokopos and Pappas lagoons, the forested slopes that would provide excellent hunting possibilities and the fertile plains spreading between the two major rivers of the region, Peiros and Larissos, give the reasons for the long term occupation of the site, beginning in the final neolithic period (ca. 3500 B.C.) and continuing, almost without a break, until medieval times (17th cent. A.D.).