The narrow entrance to the mine which takes the visitor right into the mountain lies two hundred metres above the valley. After a few metres, visitors encounter huge, 20-metre-high halls supported by slate pillars that serve to prop up the hollowed-out mountain. The impression of such spaces takes your breath away. In Elm, a small slate factory has been preserved; this has been turned into a museum. Each stage of production, from the drawing of lines to the framing of the small slate tablets is replicated and explained during tours through the old hand-finishing areas.