Pozu Sotón Monument · San Martín del Rey Aurelio, Nalón, Asturias A vertical shaft at El Entrego declared a Bien de Interés Cultural (Spain's highest level of heritage protection), the only one in Spain that allows visitors to go down into its galleries in miner's gear; beside its headframe stands the memorial to the victims of mining accidents. Photo: LMLM (CC BY-SA 3.0) What to see and do in San Martín del Rey Aurelio