Espartinas Salt Works Monument · Ciempozuelos, Las Vegas, Madrid Salt-working site declared Bien de Interés Cultural (Spain's highest level of heritage protection) in 2006 and listed as a site of geological interest; excavations from 2001 to 2004 documented evaporation ponds and artificial caves occupied since the late Neolithic. It extends through the Valdelachica valley, at the foot of the gypsum escarpments on the right bank of the Jarama, and it was the place where the mineral thenardite was discovered. In 2006, fifteen sites linked to salt extraction were counted in the surrounding area, among them evaporation ponds, artificial caves and the remains of the old convent of las Salinas, next to the mine and the spring of mother waters that supplied the works. Photo: Rodelar (CC BY-SA 4.0) What to see and do in Ciempozuelos