Cape Sounion is the promontory at the southernmost tip of the Attic peninsula, 8 kilometres south of the town of Lavrio, and 70 kilometres southeast of Athens. It is part of Lavreotiki municipality, East Attica, Greece. It is 59.6 km away from Athens.
Cape Sounion is noted for its Temple of Poseidon, one of the major monuments of the Golden Age of Athens. Its remains are perched on the headland, surrounded on three sides by the sea.