File:Temple of Poseidon - Northern fascade.jpg

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 father of the hero Theseus, although the mortal Aegeus also claimed this distinction. Theseus was happy to have two fathers, enjoying the lineage of each when it suited him. Thus he became king of Athens by virtue of being Aegeus's son, but availed himself of Poseidon's parentage in facing a challenge handed him by King Minos of Crete. This monarch threw his signet ring into the depths of the sea and dared Theseus to retrieve it. The hero dove beneath the waves and not only found the ring but was given a crown by Poseidon's wife, Amphitrite.