|Summary:||Wall with towers and gates; surrounding the town on the western side of the promontory, also enclosing the Sanctuary of Poseidon.|
|Date:||ca. 450 BC - ca. 400 BC|
Area covered: ca. 350 m x 220 m.
Abuts peribolos wall of Sanctuary of Poseidon on southern end running north then west to the western coast of the peninsula. Ten towers of varying size at irregular intervals. A small gate between (counting from the wall's southern end) towers 2 and 3, was enclosed by a later bastion. The main entrance was at the western end.
The promontory was fortified during the Peloponnesian war. The small gate near the sanctuary later became an interior entrance to the bastion, which may date to 263-229 B.C. The section of the wall running east-west was less finely built than walls running north-south, possibly because steeper terrain there offers greater natural protection. The main entrance toward the western end was protected by a large rectangular building, possibly a guard house or barracks.