The ancient sanctuary built by the Athenians in honour of Poseidon, the mighty god of the sea, stands tall on top of a natural hummock surrounded by water on the southernmost edge of Attica. According to the myth, the dispute between Athena and Poseidon over the domination of Attica ended with Poseidon’s defeat when the king of Athens chose the sacred olive over Poseidon’s sea horses. Still, Athens has always been heavily dependent on the sea. The cult of Poseidon eventually found its rightful place on the highest part of Sounion cape, which was always considered to have great military importance because it controlled the entrance of the gulf of Saronikos. The promontory was fortified with powerful walls quite early on, and was always guarded by well trained men. There was also a naturally formed harbour underneath Sounion, used as an advanced naval port with its very own shipyards. Keeping up the promontory guard was always a major concern for the Athenians.
We now know that the area was already considered sacred during the Archaic period thanks to the kouri of Sounion, which are now exhibited in the National Archaeological Museum. They were found buried near the top of the hill and comprise our only evidence that the Sanctuary of Sounion was already accepting important offerings in 600 B.C. The construction of an imposing poros temple dedicated to the god of the sea had been initiated long before 480 B.C. and during the Persian invasion it was already in a very advanced stage. Unfortunately when the Persians finally left, all that remained of the temple was a heap of ruins. 
     The Athenians started a new building project during Pericles’ Golden Years, resulting in the construction of a new temple, placed between 444 and 440 B.C., when the city was at its peak. The hilltop was flattened especially for this purpose and the remains of the old temple were removed and finally incorporated in the fortification walls. The new temple was Doric peripteral, with two columns between the antae of the pronaos and the opisthodomos and was entirely made out of Parian marble. There was a relief frieze depicting a Centauromachy running down the length of the pronaos, while other statues - preserved in very poor condition - decorated the pediments and the peaks of the roof. Its great similarity to the Hephaisteion (Theseion) in the Ancient Agora of Athens could mean that they were designed by the same architect. 
The monument remained standing for more than two millenniums. From the 18th century onwards it was repeatedly ransacked and today some of its columns have appeared in Chatworth (England), in Venice and in Potsdam (Germany). The remains of the sacred temple have become a warning sign for seamen that they are approaching the entrance of the Saronikos. The sanctuary of Poseidon, standing tall in all its whiteness, is commonly known among them as Kavokolones (cape columns) and has inspired many travellers, romantic writers and poets. The incredible view of the archipelago and the magic sunsets make this amazing construction even more unique.