The prisons of Venice were found inside the Doge's Palace. The most inhospitable were situated on the ground floor, and came to be known as the Pozzi (or 'wells') - they were 18 cells – dark and lined with wood, and connected by bleak, murky corridors. Here, the living conditions were terrible: under the wooden tables lurked every type of insect, food was scarce and inedible, the air suffocating, and the environment overcrowded.

The famous Piombi were housed in rooms under the roof. They owe their name to the slabs of lead that covered the roofs, making these rooms extremely hot in summer and ice-cold in winter. These rooms were in general, designated to upper-class inmates or to those awaiting trial.

The most famous guest of the Piombi was Giacomo Casanova, who ended up in prison after a long series of crimes and was the protagonist of the most famous and fantastical of escapes: having climbed onto the prison roof, Casanova managed to slide down a drain pipe, slip inside the Palace and then persuade someone to open the door, in order for him to then escape calmly on a gondola. Not, according to legend, without first allowing himself a coffee in the Piazza San Marco.

The New Prisons, rather, were found beyond the Palazzo river, and these were accessed across the famous Bridge of Sighs.