I Piombi, »the Leads«, were the most infamous cells in the Old Prison of Venice, located directly under the lead roof of the Doge's Palace and regarded as impervious to jailbreak. They were six in number, and reserved for prisoners having committed particular crimes — those which were either exceedingly grave or conversely, relatively slight but touchy to handle. Their location made them boiling hot in summer, cold as bleak hell in winter and at all times presumably a risk of lead poisoning, although the Venetians appear to have either not known or not cared. In spite of this, they were better than the other cells of the Old Prison, the so-called Pozzi, »Pits« or »Wells«, cramped holes whose nature is accurately delineated by their name. The Leads are famous now mainly because of Giacomo Casanova's escape from one of the cells, which he described first in the pamphlet The Story of My Escape (claiming that he was sick and tired of repeating the tale to querents) and then, somewhat later, in his memoirs, the writing of which was possibly spurred by the success of the first work.
By Casanova's time, the Leads were all that was left in active use of the Old Prison, the Pits having been decommissioned long before, after the construction of the New Prison across the canal in the year 1600 made these insalubrious oubliettes obsolete. The Leads themselves were taken out of use in 1797, after Napoleon's conquest of the Serene Republic.
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