Driving aachen to ypres to Dunkirk to bruges. Is masternich worth a day?
You mean Maastricht? Sure, if you have the time. It's a pretty, old and interesting town.
If you love bookstores and repurposed buildings, you can check out this beautiful bookstore: https://mymodernmet.com/merkx-girod-selexyz-dominicanen-maastricht-bookstore-church/