Cape Sounio is situated at the southern most tip of Attica, and has a strategic value to be able to guard the entrance to the Salonic Gulf.
During the Peloponnesian War, in the winter of 413/412 BCE, the Athenians fortifired the Poseidon's sanctuary with circuit wall. Later in the third century BCE, the Macedonians extended the fortification. In the photo right is the eastern fortification wall of the eastern, and below is the remains of the bastion attached to it, constructed by the Macedonians.
In the photos left and below is the remains of the northern fortress.
Around 100 BC, the slaves of the Laurium (silver mine) revolted and occupied this fortress for some time, probably for some years, ravaging the surrounding country (Posidonius, FGrHist 87 F35).
