Royal Prison of Forced Labourers Monument · Almadén, Valle de Alcudia, Ciudad Real Image of Almadén, not of the place itself. A prison built around 1754 by the engineer Silvestre Abarca to house convicts sentenced to forced labour in the mines. It remained in operation until 1800. Photo: Lluís Marià Vidal i Carreras (Public domain) What to see and do in Almadén