Being that close to Brussells, that would be a major travel hub. Get a Benelux train pass, which has unlimited travel for a predetermined time inexpensively. I lived in Luxembourg while going to school, and toured there a lot. Seriously try and hit Brugge. Undamaged through the wars, drinking in the town square by the tower that was put up in 900ad in a tavern that's been there since that time as well. Then hop into the train to Amsterdam.