Roc-la-Tour is the name of a site located at an altitude of 400 m in the forest of Château-Regnault on the heights of Monthermé, in the Ardennes, at the confluence of the Meuse and Semois, characterized by quartzite columns that would be the remains of a hypothetical "castle of the devil". The place is one of the oldest sites visited in the region. The traces of the first travelers discovered in the 1970s date back about 15,000 years. By decree of 20 August 1935, Roc-la-Tour is classified as a natural site on the basis of artistic, picturesque, scientific, historical, and legendary criteria.