The original, Archaic-period temple of Poseidon on the site was built of tufa. The Sounion Kouros, discovered in 1906 in a pit east of the temple alongside fragments of other statues, was probably one of a number of votive statues dedicated to Poseidon which probably stood in front of the god’s sanctuary. The archaic temple was probably destroyed in 480 BC by Persian troops during Xerxes I’s invasion of Greece. After they defeated Xerxes in the naval Battle of Salamis, the Athenians placed an entire captured enemy trireme (warship with three banks of oars) at Sounion as a trophy dedicated to Poseidon.
Temple of Poseidon at Cape Sounion, built circa 440 BC.
The temple of Poseidon at Sounion was constructed in 444–440 BC. This was during the ascendancy of the Athenian statesman Pericles, who also rebuilt the Parthenon in Athens. It was built on the ruins of a temple dating from the Archaic period. It is perched above the sea at a height of almost 60 metres (200 ft). The design of the temple is a typical hexastyle, i.e., it had a front portico with six columns. Only some columns of the Sounion temple stand today, but when intact it would have closely resembled the contemporary and well-preserved Temple of Hephaestus beneath the Acropolis, which may have been designed by the same architect.
As with all Greek temples, the Poseidon building was rectangular, with a colonnade on all four sides. The total number of original columns was 36: 15 columns still stand today. The columns are of the Doric Order. They were made of locally quarried white marble. They were 6.10 m (20 ft) high, with a diameter of 1 m (3.1 ft) at the base and 79 cm (31 inches) at the top. At the center of the temple, colonnade would have been the hall of worship (naos), a windowless rectangular room, similar to the partly intact hall at the Temple of Hephaestus. It would have contained, at one end facing the entrance, the cult image, a colossal, ceiling-height (6 metres (20 ft)) bronze statue of Poseidon.