The Temple of Poseidon was built around 520 BC. in a Doric pavilion, with 6 columns on the narrow and 12 on the long sides. It is one of the three great sanctuaries of Poseidon in the Saronic Gulf. The temple forms an isosceles triangle with the temples of Aphaia in Aegina and Poseidon in Sounio.

To the southwest of the church is a building that is believed to have been the Bouleuterion of the city of Kalavria. The representatives of the seven cities that participated in the Amfiktionia of Kalavria also met there. To the southwest of the Bouleuterion there was a building (the monument of Demosthenes or the Asclepieion).

The orator Demosthenes took refuge in the sanctuary and sought asylum, persecuted by the Macedonians, who had occupied Athens. In the end, the great orator of antiquity, committed suicide by drinking poison and was buried in the sanctuary in 322 BC. The sanctuary is located in Palatia, between Vigla and Profitis Ilias.