D1-D2 Luxembourg City → D3 Vianden and the Ardennes → D4 Mullerthal → D5 Echternach and the Moselle Valley → D6 Departure. The entire trip is connected by trains and free buses, with no need for a car.
Take a bus for about 1 hour to reach the Ardennes town of Vianden and visit one of Europe’s best-preserved medieval castles. Climb the tower for views over the Our River valley; the former residence of the great writer Victor Hugo during his 1871 exile is also worth a visit at the museum. In the afternoon, stop by Clervaux Castle or Bourscheid Castle.
Based in Berdorf-Clausen, hike the classic Route B loop, passing through sandstone gorges, stone bridges, and forests. The full route is about 11 km, ending in the small town of Steinsel-sur-Sûre, which has a mini museum and riverside cafés. Those with limited energy can choose the 4 km short loop.
In the morning, explore the monastery old town of Echternach, Luxembourg’s oldest town. In the afternoon, head south to either Battemberg or Schengen: stand at the tri-border area by the Moselle River, read the text of the Schengen Agreement engraved on the stone monument, and finish with a glass of local Riesling.
Return to the capital to pick up sparkling wine and chocolate souvenirs, then depart from the airport or via high-speed rail through Brussels, Paris, or Frankfurt.