The prison of the Princes of Monaco, the duke of Valentinois from 1642 to the French Revolution. On the door's lintel we notice the coat of arms of the Grimaldi family.
To compensate him for the sacrifices made in the struggle with Spain, Louis XIII granted the Duchy of Valentinois to the Prince of Monaco under the Treaty of Péronne in 1642. They remained Duc de Valentinois until the French Revolution.
The coat of arms of the Princes of Monaco, above the door, is engraved on stone, surrounded by a molded frame and surmounted by a prince's crown: "Argent 15 fusées Gules".
The house is 4 storeys high, including the cellar and attic. Each floor contains a medium-sized room with a dungeon at the back, lit only by a dormer window. Set back from this was a small house housing the jailer, who could keep an eye on everything. From 1690 to 1780, it housed fraudsters, troublemakers and others involved in petty theft and robbery.
However, as they did not offer all the security advantages desirable in a busy part of the Upper Town, on July 3, 1775, the Attorney General of the Grenoble Parliament ordered them to be repaired (as they were too narrow and unsafe) or rebuilt. If necessary, new ones were to be built: the prisons on rue Peyrolerie.
The prisons on the warm hillside were named Vieilles prisons when they were replaced by new ones in 1780.
