English: The sacred promontory of Sounio, as Homer called it in his Odyssey, is situated on the SE edge of the peninsula of Attica, 67 km from Athens. On the highest point of this isolated cape, at the height of 70m from sea level, are the ruins of the Temple of Poseidon; the "Cavo Kolones", as sailors call them.

The temple of Poseidon was constructed in c.440 B.C., over the ruins of a temple dating from the Archaic Period. It is perched above the sea at a height of almost 60m. The design of the temple is a typical hexastyle i.e it had a front portico with 6 columns. Only some columns of the Sounion temple stand today, but intact it would have closely resembled the contemporary Temple of Hephaestus on the Acropolis, which may have been designed by the same architect.

Poseidon was brother to Zeus and Hades. These three gods divided up creation. Zeus was ruler of the sky, Hades had dominion of the Underworld and Poseidon was given all water, both fresh and salt.

Although there were various rivers personified as gods, these would have been technically under Poseidon's sway. Similarly, Nereus, the Old Man of the Sea, wasn't really considered on a par with Poseidon, who was known to drive his chariot through the waves in unquestioned dominance. Poseidon had married Nereus's daughter, the sea-nymph Amphitrite.