Paestum is the classical Roman name of a major Graeco-Roman city in the Campania region of Italy. It is located near the coast about 85km. SE of Naples in the province of Salerno and belongs to the comune of Capaccio.

Founded around the start of the 7th century BC by Greek colonists, and originally known as Poseidonia, it later became the Roman city of Paestum in 273 BC after the Graeco-Italian Poseidonians sided with the loser, Pyrrhus, in war against Rome during the first quarter of the 3rd century BC.

The city remained in continuous occupation throughout the Roman imperial period, but started to go into decline between the 4th and 7th centuries, probably due to changes in local land drainage patterns leading to swampy malarial conditions. It was abandoned during the Middle Ages, and its ruins only came to notice again in the 18th century, following the rediscovery of the Roman cities of Pompeii and Herculaneum.

The main features of the site today are the standing remains of three major temples in Doric style, dating from the first half of the 6th century BC. Of these, two were dedicated to the Greek goddess Hera and the third to Athena, although they have traditionally been associated with the names of the Roman deities Poseidon, Neptune, and Ceres, due to 18th century mis-attribution.

The town of Paestum, directly to the north of the architectural site, is a popular resort.