Built in the same time as Parthenon, the Doric Temple of Poseidon is situated on the edge of the magnificent Cape Sounio, 70km south from Athens. 16 remaining slender columns of Doric order reveal that Greeks, indeed, knew where to "place" their temples. On the coast of Attica, Cape Sounio is a jewel overlooking the Aegean Sea. Once upon a time, the Temple of Poseidon used to serve as a sacrifice point, since the sailors tried to appease God of the Sea, Poseidon, before entering the Aegean Sea.
The distinctive cape crowned with the imposing Temple of Poseidon offers impressive views of the Saronic Gulf and the Aegean Sea with the Greek islands. http://www.thisisathens.org/explore/venues-attractions/12-attractions/temple-of-poseidon/