Prehistoric mines of Texeo Monument · Riosa, Oviedo, Asturias Copper and cobalt workings opened some 4,500 years ago on the eastern slope of the Aramo, between 1,200 and 1,600 metres; the engineer Van Stralen rediscovered them in 1888 along with 191 human remains of miners in the galleries. Photo: No machine-readable author provided. Arbeyu~commonswiki assumed (based on copyright claims). (CC BY-SA 3.0) What to see and do in Riosa