Samuño Valley Mining Ecomuseum and Railway Monument · Langreo, Nalón, Asturias Opened on 15 June 2013 around the San Luis shaft in Ciaño, deepened between 1928 and 1930 by Carbones de La Nueva and declared a Bien de Interés Cultural (Spain's highest level of heritage protection); it remained in operation until 1969, when Hunosa stopped working it, and its definitive closure came in 2002. The visit is made by mining train from El Cadavíu station, which runs across the valley on the surface — between spoil heaps and the Trechora mine entrance, in the Protected Landscape of the Mining Basins — and goes underground through the Emilia adit to the first level of the shaft, thirty-two metres below ground, on the longest underground railway route inside a real mine in Spain; the shaft reaches 420 metres spread over six levels, and visitors return to the surface by lift. Photo: Hector Amato (CC BY-SA 4.0) What to see and do in Langreo