Large-scale coal mining was the principal economic activity in the province of Asturias in northern Spain from the 1840s. Langreo, with a population of 43,000 is the fourth largest town in the province and lies close to the River Samuñ which extends 8 km from its source to its confluence with the River Nalon. The whole valley is full of the evidence of past industries, with mines of many types, including adits, shafts and open-cast workings, railways, inclined planes, aerial ropeways and waste tips colonised by vegetation. The whole landscape is now under legislative protection.
The museum at Cadaviu in the parish of Ciaño in the municipality of Langreo opened to the public in 2013 after a campaign lasting many years. In this area as in many other parts of Europe, the conservation and rehabilitation of the industrial heritage are combined with projects for economic revitalisation. The reception area of the museum is at El Cadaviu station where there are displays of tools and mining equipment, historic photographs and audio visual programmes on the history of the area. Visitors can then begin two-hour guided tours, embarking first on trains made up of specially-designed carriages which go 1.1 km underground. They then take a lift which rises 30 m to the surface area of the Pozo St Luis (St Louis Mine) opened by the Carbones de la Nueva company in 1928-29. The steel headstocks and the buildings, with stepped gables, are of outstanding architectural quality. Production of coal at the Pozo St Luis ceased in 1969, but some machinery remained working to enable continued operation of neighbouring collieries, until final closure came in 2002. Visitors can see the lamp house, the bath house, ventilation fans, the medical centre, the forge and the office where workers were paid. There is also a display of locomotives, and from time to time there are demonstrations of steam workings by a shunting locomotive built in Munich by Maffei in 1920. There are also displays about other collieries in the valley, and trail guides enable visitors to explore their remains.