Since its creation, the Ducal Palace was the location of the political representation of the town. The Augusta Fortress of Castruccio Castracani was built here in the 14th century; the Citadel in the 15th century; and then the Public Palace.

After the explosion in the armoury in 1586, the complex was redesigned by Bartolomeo Ammannati and then by Filippo Juvara. Under the Principality new works were carried out by Lorenzo Nottolini. After the unification of Italy it was stripped of its vestments and equipped with courtrooms.

During the fascist regime it hosted various fascist demonstrations; in particular in September 1930 when Mussolini gave his official speech there in front of the crowd gathered in the square.

In 1944, it was the seat of the prefecture of the Salò government.

During the hectic hours leading up to the arrival of the Allies, on the evening of 4 September 1944, one of the two courtyards of the palace, the so-called 'Swiss' courtyard, was the gathering place for the partisans ahead of the uprising.

The announcement of the Liberation was then made from the balcony on Piazza Napoleone. In the following days, meetings of the no longer clandestine CIn were held here.

Since 1989 it has housed the Museo del Risorgimento (Museum of Unification of Italy), which was founded in 1925.