Located at the southernmost tip of the Attica peninsula in Greece, the Temple of Poseidon at Sounion is surrounded on three sides by the sea. It was constructed in approx. 440 BC, over the ruins of a temple dating from the Archaic Period. Only some columns of the Temple of Poseidon stand today, but intact it would have closely resembled the Temple of Hephaestus beneath the Acropolis, which may have been designed by the same architect.