The unmissable four
1. Vianden. The castle is the country's single best sight outside the capital — dramatic, well-restored, and reachable by CFL train to Ettelbruck then bus 570. Allow a full day. 2. The Mullerthal from Echternach. Luxembourg's "Little Switzerland" has the best hiking in the country; Trail 2 from Berdorf covers the sandstone gorges. 3. The Moselle wine villages — Remich, Ehnen, Wormeldange — for Crémant de Luxembourg and river-terrace lunches. 4. Trier, just across the German border, for Roman ruins including the Porta Nigra and the Kaiserthermen.
These four give you four different countries' worth of variety in a country the size of Rhode Island: medieval fortress, sandstone canyon country, Riesling terraces, and Roman capital. Vianden and the Mullerthal work best as full days; the Moselle can be a half-day if you’re driving. Trier is 45 minutes by train from Luxembourg Gare and free with a cross-border ticket. All four beat almost anything else you could do with a second or third day in the country.
Four more solid picks
5. Clervaux, in the Ardennes north, for Edward Steichen's "Family of Man" photo exhibition at the castle — a UNESCO Memory of the World listing. 6. Esch-sur-Alzette and the industrial heritage at Belval, where blast furnaces have been converted into a university campus and cultural venue. 7. Mondorf-les-Bains for the thermal spa, a genuine day-long soak. 8. Bourscheid Castle, a ruined hilltop fortress in the Ardennes with huge views over the Sûre valley.
Clervaux is the pick if you care about photography — the Steichen show is world-class and most visitors have never heard of it. Belval is interesting rather than beautiful; go if you like industrial architecture. Mondorf works as a rainy-day plan. Bourscheid pairs well with Vianden if you have a car. Skip Echternach town itself as a standalone — it's the trailhead for the Mullerthal, not a day trip on its own merits.
Good to know
Which is best without a car?+
Vianden, Trier and Clervaux are all easy by train and bus. The Moselle needs a car or an organised wine tour to be worthwhile.
Can I combine two in one day?+
Vianden and Bourscheid work together by car. Otherwise, one place per day — the country is small but the connections aren’t fast.