The rail line from Luxembourg to Liege penetrates the heart of the Ardennes Forest, site of the infamous World War II Battle of the Bulge. At Ettelbruck, an intermediate station, there’s a public square and monument honoring American General George S. Patton. At Clervaux, another stop, there’s a museum devoted to the battle itself.
The route is scenic as well as historic, winding through steep, attractively-forested hills and valleys with many quaint small-town train stations and other old buildings along the way. The railroad provides a far more intimate view of the countryside than a highway would, and seeing this terrain up-close will help you understand why the Battle of the Bulge was such a long and bloody one.
Just a short round trip from Luxembourg to Ettelbruck, Diekirch or Clervaux and back will introduce you to the Ardennes and provide two chances to photograph Old City Luxembourg from the high viaduct over the Alzette River Valley. (This viaduct is NOT safe to walk across.) Otherwise, I’d recommend making the Luxembourg-Liege trip part of a longer itinerary.
The rail trip from Luxembourg to Brussels isn’t as scenic as the one through the Ardennes, but it’s on a high-speed train that will get you there in less than three hours. This is another route that I’d suggest incorporating into a longer itinerary. I first discovered Luxembourg as a stopover on a roundabout circle trip from Amsterdam to Paris and back. My latest visit was on a Copenhagen-Brussels journey. My third? Not sure yet, but there WILL be one. It’s hard to go wrong adding a day in Luxembourg to any European itinerary.