Bridge of the Sighs
The bridge of the Sighs, architectural work of the late '500, is composed by two corridors superimposed that put in touch the Palace of Justice and the ancient jails with the cells that are beyond the canal of the Building. It's told that it could be heard the sighs of the prisoners when they passed the bridge, because they could not escape
  anymore. The Old Jails were the ancient jails of the Doge's Palace, and were divided in Leads, that is cells set under the lead roofs of the Building that housed famous personages like Casanova, Manin, Pellico and Tommaseo, and in Wells, narrow places at the ground floor that were damp and dark reserved to the condemned for the most serious crimes and to the political prisoners.