Built between 1605 and 1606, it was fed by a spring located near the Citadel, rainwater and the Magistral Aqueduct.
The vast chamber extending under the square could collect up to 1,300 cubic meters of water.
The only element that suggests its presence is a simple well whose structure is reminiscent of Venetian wells.
It was erected in 1763 by order of prefect Marino Cavallo, as recalled by an engraving still visible on the left side.
In the 19th century it was transformed into a fountain by installing a plunger pump.