The Mattatoio (slaughterhouse) is located in an area of considerable archaeological importance that once housed commercial and residential structures. The main building, designed by Gioacchino Ersoch and built between 1888 and 1891, originally served as the slaughterhouse and cattle market.

The Pavilions are located along the eastern perimeter of the former slaughterhouse complex and were originally used as stables (27a and 2a, part) and entrance (28b).

Pavillion 27a has a very elongated rectangular shape, with a height of approximately 6m and a double-pitched roof. The structure is in a state of total abandonment and part of the roof was destroyed by a recent fire.

 Pavilion 28b has a practicable flat roof and consists of two covered side bays that allow the entrance to the Campo Boario, as well as three closed central rooms, formerly used as the guardhouse. Pavilion 2a corresponds to the portion of a rectangular building along the Piazza Giustiniani façade. It has a double-pitched roof, formerly occupied by a discotheque, and is currently in a state of disrepair. One of the buildings houses a depository of Monte dei Cocci artefacts.

Within the overall framework of the restoration of the Ex-Mattatoio di Testaccio monumental complex, the project will have the following objectives:

• recover the original appearance of the Pavilions;
• make evident the traces left by the transformations that the Pavilions have undergone over time;
• reconcile the new requirements of functionality with the legibility of an industrial archaeology artefact of primary importance.