The Castello Visconteo is a large brick fortress at the northern edge of the old city, now housing the Musei Civici — Pavia's main civic museum. The archaeological collections include Roman inscriptions and mosaics from the ancient city of Ticinum; the medieval galleries have Lombard-era artifacts and carved capitals from demolished churches. The pinacoteca upstairs holds paintings from the 14th to 18th centuries, with some good Flemish work acquired by the Viscontis and Sforzas.
The castle itself is worth walking around even without entering: the large courtyard gives a sense of the scale of Visconti ambition, and the towers overlook a park that was once the castle's hunting ground. One of the wings was destroyed in the Battle of Pavia (1525), where Francis I of France was captured by Charles V — one of the decisive moments of the Italian Wars.