Poseidonia was the original name for the Roman city of Paestum, situated south of Naples, founded by Greek colonists around 600 BC. It was partly flooded and largely forgotten until a number of well-preserved Greek temples were rediscovered in the 18th century.*
Coincidentally, the city was established in a region of southern Italy, described by Plato as being part of Atlantean territory!*
Poseidonia, is also the name of a village on the Cycladic island of Syros.