The building, considered until the 18th century a model humanitarian prison, was designed by Del Grande following a detailed program of Virgilio Spada and keeping in mind the prisons of Tordinona.
It was organized in two blocks: the one of the representations and the parlors, on Via Giulia, and the one of the dungeons towards the Tiber; the two bodies are connected by a gallery open on the side courtyards.
It is possible that the planimetric shape - similar to a sword coming out of a hilt - represents an allegory either of the justice of Pope Innocent or of Virgilio Spada ("Sword" in English) himself, superintendent of the construction.

The building is built with bricks with overhang in rustic travertine or stucco.
It has 4 floors with 6 windows each on the main facade along Via Giulia.
On the ground floor the windows are rectangular and equipped with grilles.
At the center of the ground floor there is a strongly tapered  portal with at the center of the lintel a large bugna surmounted by the inscription cited  above.
The imposing building is concluded by a large groove cornice.
The building, considered until the 18th century a model humanitarian prison, was designed by Del Grande following a detailed program of Virgilio Spada and keeping in mind the prisons of Tordinona. It was organized in two blocks: the one of the representations and the parlors, on Via Giulia, and the one of the dungeons towards the Tiber; the two bodies are connected by a gallery open on the side courtyards. It is possible that the planimetric shape - similar to a sword coming out of a hilt - represents an allegory either of the justice of Pope Innocent or of Virgilio Spada ("Sword" in English) himself, superintendent of the construction.
The building is built with bricks with overhang in rustic travertine or stucco. It has 4 floors with 6 windows each on the main facade along Via Giulia. On the ground floor the windows are rectangular and equipped with grilles. At the center of the ground floor there is a strongly tapered  portal with at the center of the lintel a large bugna surmounted by the inscription cited  above. The imposing building is concluded by a large groove cornice.
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