Together with those in Shoe Market Square and Mascheroni Square, it constituted the system of cisterns capable of ensuring the population a considerable water supply during droughts, as well as during any periods of siege.
It was fed by the Magistral Aqueduct and was the largest of the Upper Town cisterns.
In the center of the long side of the cistern, a marble plaque recalls that the Fontanone was built in 1342 to a design by Giovanni da Corteregia and Giacomo da Correggio, at the time of the rule of the Visconti Seigniory of Giovanni and Luchino Visconti.