The Fitzwilliam is Cambridge's main public museum and one of the finest collections in Britain — almost entirely overlooked by visitors who spend all their time in the colleges. The Egyptian antiquities room is excellent, with sarcophagi, shabtis, and papyrus scrolls. The paintings collection includes Italian masters, Dutch and Flemish work from the 17th century, and a strong group of French impressionists. The applied arts galleries cover European armour, English pottery, and medieval illuminated manuscripts.
Entry is free. The museum is open Tuesday to Saturday 10am–5pm, Sunday noon–5pm, closed Monday. It is a ten-minute walk south of King's College along Trumpington Street. Do not skip it in favour of a second pass through the colleges — it is better than most of what you'll pay to see.