The rising of the first nucleus of the Sforzesco Castle near the communal wall was due to Galeazzo II. It was later extended by his successors Giovanni Maria and Filippo Maria. After its destruction by the Milanese during the Ambrosia Republic (1447-50), Francesco Sforza undertook the reconstruction of the castle in order to consolidate the dynasty continuity between his power and the Viscount's dominion, determined by his marriage to the daughter of Filippo Maria, Bianca Visconti.
These days it houses several Cultural Institution Headquarters such as Library Of Civic Arts, Photograph Civic Library (Picture Gallery), the Bertarelli Civic Collection of Engravings, The School Of Civic Arts, The Civic Collection Of Antique Arts and Applied Arts, among others. The immense public inheritance with around 32,000 fine art paintings, sculptures, and designs can be admired in the museum of Antique Arts.