The entirety of the old town is classified as a UNESCO World Heritage site. Highlights include the Gëlle Fra, the Cathédrale de Notre-Dame, the view from the Pont du Grund, the remains of the city fortifications, the Bock Casemates, and the panoramic elevator in Paffendall.
Explore the hiking trails of the Mëllerdall region, known as Luxembourg's "Little Switzerland" and classified as a UNESCO Global Geopark. Highlights include the Schéissendëmpel ("Shoot-Pond") waterfalls and the Wollefschlucht ("Wolf-Canyon") rock formations.
Explore Luxembourg's wine region along the Musel (Moselle) River. Rick's dad (the family wine connoisseur) recommends Schlink Domaine Viticole, Domaine Viticole Schumacher-Lethal, and Caves Henri Ruppert.
Go for a swim in Luxembourg's biggest lake.
While we are partial to the castle in Larochette, Vianden is also quite pretty and a great little village to explore.
The legal basis for your travel to the European Union was signed here, so for the political aficionados this might be an interesting visit... although Rick says 30 minutes will be "more than enough."