Metal ore, mainly galena and zinc blende, has been mined in Bad Grund in the Upper Harz since the 16th century. The last German ore mine to close in 1992 was the ‘Gotteshilfe mine’, which was up to 900 m deep. This mine included the ‘Knesebeck shaft’, where the mining museum was opened in 1997. The more than 500-year history of mining is presented above and below ground. In the former operating rooms, there are exhibits such as ore steps, uniform parts, flags, vivid glass pit models and numerous underground vehicles on the extensive open-air site. Equipment and machines left on site show the technical development of the plant from the middle of the 19th century to the end of operations. Among other things, the historic winding engine and an electric compressor, both from 1923, as well as two restored wheel rooms with water wheels up to twelve metres high are on display. The landmark and probably the only preserved installation of its kind is the 47-metre-high hydro-compressor tower. It was built in 1912/13 as part of a water engineering plant that generated compressed air for the machines in the mine.