37 metres deep and 5.60 wide, the well was probably first devised as a cistern, before later being used to collect water from the underground springs. Built in the same period as the Etruscan walls, (3rd century B.C.), the well, intended for public use, was accessible from the well-curb in Piazza Piccinino and was similar to other wells present in various parts of the Etruscan acropolis. It features a singular and sturdy trussed roof, made up of five monolithic blocks.