Getting sent out on a last-minute "emergency" work trip to Maastricht, Netherlands but Leige, Belgium and Aachen, Germany are within 10-15 miles so if there's anything really interesting and worth seeing I'd be willing to make the journey.
(I've already done all the Cologne, Dusseldorf, & Munster major beer highlights so I'm really just looking at the 3 cities above.)
Adam