In Venice in every district, anciently, there were local prisons where the debtors or the Rei confessed to minor crimes were locked. These prisons were called CASONI: “in each district of this city we find a cason, or prison, in which the debtors are put” (reported by a document of the MAGGIOR CONSIGLIO of 1551).
In Cannaregio there is still a Campiello de la Cason that stands to testify that there was the local prison of that district.
Near this campiello there is the Campo Santi Apostoli where, once there were numerous dwellings of the Partecipazio, the family that gave to the Serenissima six doges: Agnello (810) Giustinian (827), Giovanni 1 ° (829), Orso 1 ° (864), Giovanni II (881), Orso II (912), Pietro (939), who had before the post of the Tribune, so right next to their homes were built the prisons.
The Partecipazio’s Palace overlooked the ancient Rio Baduario, said of the Barba, which was then buried and today is called Rio Terà Barba frutariol. The Campo Santi Apostoli extended its area to this palace and all around was uncultivated land.
Later, these small prisons were made to flow to the Piombi, near San Marco’s Square, connected by the Ponte dei sospiri, the prisons of the ducal palace from which he managed to flee only Giacomo Casanova.
A Sotoportego of Cason exists in San Zuane in Bragora, and a calle and Corte del Cason existed once in Contrada San Ziminian, but disappeared when in the 1869 dug the Bacino Orseolo, changed its name to Fondamenta.