This massive and imposing fortress dates from 1368, the era of the Viscontis, but it was rebuilt by Francesco Sforza, founder of the Sforza dynasty in Milan, after he took control of the city in 1450 and it became the residence of the Dukes of Milan. Leonardo da Vinci walked these floors, and even decorated part of the Sala delle Asse (although much restored).
Several museums are laid out in the old apartments of the castle. The Civic Museum of Ancient Art contains Michelangelo's last (and unfinished) sculpture, the Rondanini Pietà, plus furniture, sculpture and an impressive collection of paintings that includes work by many of the great names of the Italian Renaissance and later (Fra Filippo Lippi, Mantegna, Correggio, Tintoretto, Canaletto). There is also a Museum of Applied Arts (antique furniture, tapestries, weapons, ceramics, jewellery), a Museum of Musical Instruments, and a collection of ancient Egyptian mummies and other artefacts.
The castle is attached to a large and attractive tree-shaded park called the Parco Sempione –- a good spot for a picnic.