Paestum was founded around 600 BC by Greek colonists — settlers from Sybaris — who named their city Poseidonia after the sea god Poseidon. Its three great Doric temples, built between roughly 550 and 450 BC, are among the best-preserved Greek temples anywhere in the world, better preserved in many respects than anything left in Greece itself. They stand almost complete on the coastal plain south of Salerno: the Temple of Hera I (long mistakenly called 'the Basilica'), the Temple of Athena, and the magnificent Temple of Hera II, once thought to honour Poseidon or Neptune.
The city passed from the Greeks to the Italic Lucanians at the end of the 5th century BC, and then became the Roman colony of Paestum in 273 BC — and you can still walk the Roman forum, amphitheatre and streets laid out among the Greek temples. In the National Archaeological Museum beside the site is the city's most precious survival: the Tomb of the Diver, painted around 470 BC, the only complete example of Greek figurative painting to come down to us from the Archaic and Classical periods, its lid showing a lone figure diving into water.
Paestum was abandoned and forgotten in the Middle Ages, its temples swallowed by malarial marsh until they were rediscovered in the 18th century and astonished the travellers of the Grand Tour. Today it is a UNESCO World Heritage Site, and a single 3-day ticket covers the temples, the museum, and the sister Greek city of Velia (ancient Elea) further down the Cilento coast — so you can take your time over one of the great archaeological landscapes of the Mediterranean.