The Mullerthal Trail is a 112-kilometre marked walking route that loops through the forested sandstone country of eastern Luxembourg, with Echternach as its natural hub. It is laid out in three routes (Route 1, Route 2, Route 3) and a series of shorter "extra-tours" that fan out from villages along the way; the full circuit takes about a week of moderate days, but you can sample it in any direction with afternoon walks of two or three hours.
The terrain is what makes the trail distinctive — soft sandstone weathered into pillars, slot canyons, broad shelves, and overhangs through dense beech and oak forest. Streams cut through the rock in places to form small waterfalls. Trail markers (a green stylised "M") are well maintained, and the Tourist Office in Echternach sells detailed maps. Boots and a windproof layer are advisable; trainers will do for the short loops near town.