The sanctuary of Poseidon
is situated on the commanding position of Palatia on the islet of Kalaureia of Poros, c. 200 m above the sea level.
According to the historical tradition, the Athenian orator and statesman Demosthenes sought refuge in the sanctuary and committed suicide in 322 BC,
in order to avoid capture by Antipatros of Macedonia.
According to the archaeological finds, the earliest use of the site goes back to the Early Bronze Age and continues without interruption throughout the historical times.
The sanctuary was dedicated to the worship of Poseidon, but there is also evidence of a multi-faceted cult activity including minor deities and local heroes worship from
possibly prehistoric to late antique date.
Archaeological research on the site began in 1894 by the Swedish archaeologists Samuel Wide and Lennart Kjellberg, who conducted the first excavation
of the Swedish Archaeological Institute in the Greek region. In 1997 the Institute resumed a new phase of archaeological fieldwork in the area, the Kalaureia Research
Program that continues to date.
THE ARCHITECTURAL REMAINS
Though the original foundation of the sanctuary cannot be definitely dated yet, it seems that by the end of the Archaic period,
the temenos (cult place) is adorned with its first monumental buildings, while construction activities continue down to the roman times.
Most likely towards the end of the 6th century BC was erected the temple of Poseidon, in the north edge of the sanctuary.
Today are preserved only the foundation trenches and the peribolos wall surrounding the structure. It is a typical peripteral temple of the Doric
order with standard six columns on the front and twelve on the long sides.
In the 5th and 4th centuries BC building activity in the sanctuary continues with the construction of mainly auxiliary buildings that
surround and define the area of the sanctuary. During the 4th century BC, in the SW side of the temenos are erected 4 stoae (buildings A, B, C, D),
while a monumental propylon (gate) shapes the entrance to the site. Apart from the above, there are also two buildings of substantial size but of
uncertain identification: Building F has been interpreted as Bouleuterion, namely the building which housed the citizens’ council, while Building G has
been interpreted either as Asklepieion, namely temple of the god Asklepios or as "Heroon (hero shrine) of Demosthenes".