This salt mine is still in use. It is a few hundred meters under the surface and the layer of salt extends over a hundred miles into Switzerland. The salt is mostly used by the chemical industry. Some of these halls are hundreds of meters long, twenty meters wide and high. They are also used to store chemical waste, e.g. from industrial filters (the big white bags that you see at the end of the movie). If you are interested in a tour: the entrance is in Bad Friedrichshall.