With a capacity of 1,800 cubic meters of water, it is one of the three large cisterns in Bergamo Alta, along with those in Piazza Mascheroni and the Fontanone.
Located below the level of the square, it was fed by the Magistral Aqueduct: from here the aqueduct’s route continued down from Via Porta Dipinta to feed its namesake fountain.
The reservoir was born from a design by architect Alessio Agliardi, who stipulated that water should be drawn through a mouth that opened onto the square.
The mouth was replaced with the present fountain in 1795 to facilitate the flow of carts and carriages.