On the Greek mainland facing the Cyclades Islands and the Aegean Sea the Sunium promontory stands out from the Attic land. Whenyou have rounded the promontory you see a harbor and a temple to Athena of Sunium on the peak of the promontory. Pausanias
Cape Sounio, Photo: Immanuel Giel , 2 February 2006
The Poseidon Temple at Cape Sounion is described in the beginning of a book of Pausanias as Temple of Athena. He did not know that there was an Athena Temple near the Poseidon Temple but it was destroyed and its remains were used for buildings of the Athenian Agora .
Poseidon Temple [Source]
Plan of the Poseidon Temple [Source}
Lord Byron Inscription, Cape Sounion
A. B. Tataki, Sounion the Temple of Poseidon (ISBN: 089241104X)
Medieval Greece / Byzantine Empire