This route leads through Mendrisiotto, a traditional wine-growing region with an abundance of testimonies to history and art, sited amidst an impressive landscape.
Erosion caused the mountain to collapse and the vast, pale yellow and reddish rock basin to form, which becomes bigger every year. From the Grabenrad or the Illhorn (2,716 m) there are "fear inspiring" yet stunning views down into the Rhone valley.
If brooks and rivers run only sluggishly above ground, hydropower is nearly impossible to harness. That is why the inhabitants of the valley of Le Locle began to use subterranean streams. This is how the cave mills of "Col-des-Roches" arose.