M Museum Leuven occupies a striking building on Vanderkelenstraat, opened in 2009, that wraps a contemporary glass and steel structure around a neoclassical 19th-century core. The result is one of the better recent museum renovations in Belgium: the new wing doesn't overwhelm the old, and the rooftop terrace offers good views over the city centre.
The collection ranges from Romanesque sculpture to contemporary Belgian art, with the medieval and early modern holdings being the real strength. Works by Rogier van der Weyden, Dirk Bouts, and other Flemish primitives from the Leuven school anchor the permanent collection. The museum also holds a large number of works documenting the city's history, which is useful context if you want to understand what you're looking at in the streets outside. Temporary exhibitions are of consistently high quality. The admission fee is modest and a combination ticket with the Sint-Pieterskerk Treasury is available.