To the right of the Basilica, is the Tempio di Nettuno (Temple of Neptune or Poseidon) the largest and best preserved of the temples of Paestum.
It was built around 460 BC, which is only 30 years before the Parthenon was constructed in Athens. Instead of the typical 20 flutes on each column, they have 24 flutes. The Temple also has a wider column size and smaller intervals between columns. The material used in the construction was local travertine, which is the bedrock in this location.
Its great and mighty structure and perfect proportions, together with some other aspects (slightly curved horizontal lines, elliptical rather than circular columns), create an impression of unshakable firmness and elegance, making this building the most perfect example of Doric architecture both in Italy and Greece.
The material found in the votive offerings (thousands of terracotta figurines representing the goddess Hera , locally manufactured vases of the Lucan age, wedding vases, gems, coins, etc.) helped determine that the temple was dedicated to Argive Hera, goddess of motherhood and fertility.
The travertine was and is being deposited in this location by the Capodiflume River, which is supersaturated in calcium carbonate in its headwaters, and has been depositing the calcium carbonate as the rock travertine in and near the stream bed and the springs in this location. Travertine is a relatively soft rock with many voids, called vugs, and can be relatively easily cut and fashioned into structural shapes. Over time took on a warm golden patina, which seems to turn itself on or off depending on the intensity of the light.
The travertine upper portions of the temples had been carved into impressive artistic designs. Some of these carved stone pieces had fallen over the ages and are now easily seen in the museum that has been built at this site. The travertine at the temple displays a coarse texture that has has many voids, so it is probably not a surprise that these voids had been filled with a finer plaster that was, in turn, painted. Some hints of paint remain in locations that are less exposed to the agents of weathering.