Crypte archéologique du vivier Romain

When you dig to build the foundations of your building, you don't expect to discover a fish pond underneath. But that's what happened to the builder of a building in Fréjus after archaeologists, having completed their preventive excavations, gave the green light to the construction site.

Instead of the solid red sandstone base on which he had hoped to found his building, the developer found a hole filled with sediment. Recalled, Pierre Excofon, one of the city's archaeologists, then discovered a square basin about ten meters on each side (8,77 x 8,33) and five meters deep. The excavation lasted two years. As the site is located between the southern rampart of the ancient city and the northern limit of its port, the archaeologists understand that this basin was located in antiquity in the immediate vicinity of the sea (today more than a kilometer away).

The single-piece basin, crossed by three arches of an aqueduct, the existence of which was not known, in no way indicates that it was in communication with the sea at the beginning, so that its first function remains mysterious.

In a second phase, the installation was converted into a fish pond: three channels were dug into the rock to supply it with sea water. The walls of the basin were cut regularly using a quarry pick whose curved furrows are still clearly visible in places.

Subsequently, a built basin is developed. This one, made of formwork, is made of a concrete mixing lime and pozzolan explained in these terms: "There is a kind of powder to which nature has given an admirable property. It is found in the country of Baiae and in the lands of the municipalities which surround Mount Vesuvius" - (Vitruvius in his De architectura - book II, chapter 6). Under ancient Rome, pozzolan is mixed with lime, allowing this mortar to set hydraulically, to harden in the presence of water. This volcanic rock is so called because it is found in the vicinity of Pozzuoli, near Naples.

The end of the operation of the fishpond is to be placed at the latest towards the middle of the second half of the 1st century AD.

Initially used as fish storage, the installation of niches and a permanent filter basin could indicate a change in the function of the fishpond, perhaps moving to breeding.

Indeed, Forum Julii – (Fréjus), was famous in antiquity for its Garum, a brine made from dried fish intestines. It was obtained by heavily salting fish fry and entrails that were left in the sun until the flesh was transformed by its own digestive juices. Pliny the Elder (23 – 79) tells us that Alex, a waste product similar to Garum, was produced in the region of Forum Julii. “The inhabitants of Forum Julii make Alex with a fish they call wolf” – Pliny the Elder – Natural History – XXI.

This production and installation illustrate the economic importance of fishing and the trade in fish products in the 1st century.

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