Sounion cape was fortified in 412 B.C. during the Peloponnesian War, in order to control and secure the ships carrying cereals to Athens. The use of various materials and construction techniques is probably the result of repairs and additions made during the Chremonides' War and the following years (266-229 B.C.). The sanctuary of Poseidon occupies the SE end of the fortress. The wall starts at the NE corner, extends to the north and turns to the west. Shipyards for the sheltering of two war ships were constructed on the coast, at the west end of the north branch of the fortification. Inside the fortress, excavations have brought to light part of a central street, remains of houses, and water cisterns.