The cellar, which was built in the Middle Ages as a cistern, i.e. a water reservoir, within the city walls, was only rediscovered in the 1990s during a clear-out.
It probably dates back to the early 14th century. From the 15th to the 19th century, it was a warehouse for a meat bank.
The early Gothic vault is fed by three "sources": rainwater that seeps in from above, groundwater that seeps in despite the rocky heights and the overflow from a well in a house diagonally above the cistern.