Visconti-Sforza Castle, Medieval castle in Novara, Italy.

The Visconti-Sforza Castle is a large quadrangular brick building begun in 1468 for Duke Galeazzo Maria Sforza, enclosing earlier structures. Only the small north-west corner turret survives of the earlier Visconti castle, with walled-up Visconti merlons and remains of the old gate. It faces Piazza Martiri della Libertà to the north, with the public gardens of the Allea di San Luca on the other three sides.

The castle was founded in the 13th century and later developed by the Visconti family, but took its current form under Galeazzo Maria Sforza in the mid-15th century. This renovation period introduced the distinctive four corner towers and reinforced fortifications that define the structure today.

The castle's name recalls two Milanese ruling houses: the Visconti, who built it in the 14th century, and the Sforza, who rebuilt it from 1468. Its courtyard served as the prisoners' exercise yard during 170 years as a prison, where Claretta Petacci, Mussolini's mistress, was held. Since 1973 it has belonged to the city of Novara.

The castle stands at the north side of Piazza Martiri della Libertà, with the public gardens of the Allea di San Luca on its other three sides. It reopened to visitors in January 2016 after almost ten years of restoration. The historic centre of Novara can be crossed on foot to reach it.

The castle became a prison in the Napoleonic era and held inmates for 170 years, until the prisons moved to the Bicocca in 1973. Among the detainees was Claretta Petacci, Mussolini's mistress. The conversion cut new windows into the medieval walls, closed others and removed the battlements.