Lille's Fine Arts Museum (Palais des Beaux-Arts) is giant—only the Louvre tops its size among France's museums—and its collection is suitably illustrious. Instituted in 1801 as part of Napoleon's push to bring art to the masses, the museum is housed in a splendid Belle Époque building dating from the late 1890s.
Stroll through the rooms and you'll find all the stars: Rubens and van Dyck, Picasso and Redon, Corot, Delacroix and David. Additionally, there is a wonderful decorative arts collection and a special curio: a selection of 18th-century models of fortified cities.
To get to the Palais, take Metro Line 1 to Republique station or bus 14 to place de la République.