The Oso valleys (Proaza, Quirós, Santo Adriano and Teverga) have had their history marked by mining. The working of their rich deposits led to railway routes that provided an outlet for their production. The mining crisis closed mines and railways. The latter have somehow returned to being experienced again thanks to their recovery as the Greenway: the Senda del Oso, which invites us on a journey through the essence of the most natural Asturias and the rustic uniqueness of places full of authenticity.