The rocks in the Mullerthal were shaped over millions of years by rain and rivers slowly eating away at the sandstone. Some boulders are as big as houses, and many have gaps, arches and caves worn into them by water. Ferns, mosses and tiny flowers grow in every crack, making the rocks look as if they are wearing green velvet coats.
The Mullerthal Trail is a famous long walking path that winds for about 112 kilometres through the region. Families walk shorter sections at a time, hopping across stepping stones over streams and ducking through narrow passages between rocks. The paths are well marked and signs often have little animal drawings to help children follow them.
The streams that flow through the Mullerthal are home to crayfish, kingfishers and frogs. In spring the forest floor turns purple and yellow with wild flowers, and in summer the shade of the trees keeps walkers cool even on hot days.
One of the most famous spots is called Schiessentümpel — a little waterfall that tumbles over a three-arched stone bridge. It is so pretty that it is one of the most photographed places in all of Luxembourg.