When the Greek colony of Poseidonia (Paestum) was rediscovered in the eighteenth century, the largest of its three temples, the "Temple of Neptune," was so named because it was thought to have been dedicated to Poseidon (actually, it is to Hera). Peristyle, the pteron has six Doric columns across the front and fourteen down the sides, a porch in the front and rear (pronaos and opisthodomos), each with two columns in antis (that is, between the extended cella walls or antae). Inside the cella are two rows of seven smaller columns and, above them, another colonnade to help support the roof.

One of the most complete and best preserved of all Greek temples, it was built in the early or mid fifth-century, perhaps not later than 460 BC, by the founders of Poseidonia, the Sybarites: An austere temple by a luxurious and pleasure-seeking people, and an example of the shock of discovery.