Inside a drab undistinguished 20th. century city lies an extremely pleasant, historic, lively city center, with cobblestone streets reserved for pedestrians and lots of outdoor summer dining and drinking.

Leuven is one of the most ancient university towns of Europe (it was Justus Lipsius') and despite an incredible number of wars, has retained (and very often painstakingly reconstructed) its historical buildings. The cathedral and city Town Hall (especially the latter) are of great architectural interest, as is the University library, rebuilt to the original splendor with American funds, which is a testament to what can be done by rebuilding on original plans. It is also a student town most of the year. In summer and good weather (neither of which are guaranteed), evenings in this decor are thoroughly enjoyable. Excellent food at reasonable prices is not hard to find, although it is not impossible to be unlucky. Ask, check. 

Trains from Brussels run every half hour, and it takes 30 mn, plus 15 mn walk,  to reach these attractive, café-ringed squares.