Almadén sits on one of the great mercury deposits of the world, and its history is one of wealth, danger and forced labour. Cinnabar, the red ore from which mercury is extracted, was mined here from Roman times, and for centuries the town produced a large share of the world's supply of the liquid metal. It was vital to the economy of the Spanish empire, because mercury was used to extract silver from ore in the mines of Mexico and Peru, so Almadén in effect fuelled the silver trade. In the sixteenth century the Spanish crown leased the mines to the Fugger banking family of Augsburg, who ran them for a long time and brought German miners to the town.
The Royal Forced Labour Gaol, the Real Cárcel de Forzados, was built in the eighteenth century to house convicts who were sentenced to work in the mines, the most hazardous job in the country. Conditions were hard, and mercury poisoning killed or crippled many. The building, a large square block with an inner courtyard, still stands, and part of it has since been used by the university for its school of mining engineering. UNESCO listed Almadén together with the Slovenian mining town of Idrija in 2012 as the Heritage of Mercury, recognising the way two mines shaped the global trade in the metal for centuries.
The setting is a surprise to many. Almadén lies in a bowl of hills on the southern edge of La Mancha, near the Sierra Morena, in a country of dehesa, rocky ridges and thin soil. The roads leading in are quiet and curving, with gentle gradients and a mix of oak woods and scrub, and the surface is generally fair. Traffic is light, but distances are long and services thin. The weather is hot and dry in summer, and cold in winter, with occasional frosts. In spring the hills are green and covered in wild flowers.
For fuel, rely on Almadén itself, which has stations, a few supermarkets and some bars, and do not rely on the villages around it, which are tiny. A walk around the old mining area gives a sense of the scale of the work, and the mine museum offers tours underground. The air smells of rock dust and rosemary, and the quiet is striking. It is a corner of Spain that few foreign riders visit, and its story is a gripping one.