In 1850, the scholar Jules Gailhabaud (born in 1810) published Ancient and Modern Monuments. Collections forming a history of architecture and people through the ages. This was an encyclopaedic work with one chapter devoted to the temple attributed to Neptune at Paestum, in southern Italy. The text was accompanied by engraved plates taken from the drawings of Viollet-le-Duc.
As well as a picturesque study of the temple, showing it in ruins for the most part, the architect provided two reconstructions: this elevation of the east facade on the one hand and on the other, the ground plan and the sections of the building. They explain the layout of the temple, in particular the colonnade of the sanctuary on two levels, which gives the temple an imposing appearance.
The layout is typical of 5th century Greek style: a colonnade - the peristyle - surrounding a partially enclosed space divided into three parts - pronaos, naos and opisthodome. The Doric order (without a base or any ornamentation) is very sober. The descriptive text emphasises the fact that no trace of any decoration was found either on the pediment or the metopes, contrary to what the architect Henri Labrouste (1801-1875) had argued in 1829 in a disputed restoration project. The statue in the sanctuary, visible in the drawing, is of a woman, whereas in the plate in Gailhabaud's book it is the statue of the god Neptune that is represented. At the time, it was thought that the temple was dedicated to him. But Viollet-le-Duc certainly had knowledge of elements proving that this temple had in fact been dedicated to Hera (Juno), and this still accepted today.