Egmont Palace is an impressive structure that has housed some of the area's most important people. Allow some time in your itinerary to view it for yourself.
You'll be spoiled for sightseeing choice when visiting Upper Town. Egmont Palace is a good place to start here, but there are plenty of other worthy sights to experience. La Grand Place, Atomium, and NATO Headquarters are near the historic stately house and will top off your day nicely.