Casa del Senato, Senate building in central Turin, Italy

Casa del Senato, also called Palazzo Longobardo, stands on the south side of Largo IV Marzo. Its stone base and traces of ogival windows survive, while the 16th-century facade has wider cross-mullioned windows in terracotta. The four-storey height, unusual for its era, and three underground levels reflect its institutional role.

Built probably on a Roman public building or with Roman materials, it is thought to have housed the Turin dukes under Lombard rule and later served as seat of the Vicarìa. Excavations directed by Riccardo Brayda during the 1890 restoration found traces of a medieval corner tower, now gone. Interior spaces were rebuilt after World War II bombings, leaving only the facade, and a restoration ran from November 2011 to early 2013.

The name Palazzo Longobardo recalls the Lombard dukes of Turin, who are thought to have used the site; later it housed the Vicarìa, the magistrate's office, together with the casaforte of Porta Fibellona. At street level, openings cut in the 20th century for shops, now closed, mark the building's long commercial use.

The building stands on the south side of Largo IV Marzo, between the former Piazza delle Erbe (now Piazza Palazzo di Città) and the Duomo, a short walk from Porta Palatina. The restoration begun in November 2011 and finished in early 2013 consolidated the 16th-century facade and added a corner tower toward via Conte Verde. Ground-floor openings made in the 20th century for shops are now disused.

The three underground levels once held the prisons of the Vicarìa; the lowest is reached only through trapdoors. The 2011–2013 restoration rebuilt a tower at the corner of via Conte Verde, recalling the medieval crenellated corner tower found by Riccardo Brayda's 1890 excavations and since lost.