The Caves of Monte Castillo, located in the Cantabrian town of Puente Viesgo, contain one of the most important Paleolithic sites in the region. The complex of caves consists of Las Monedas, El Castillo, Las Chimeneas, and La Pasiega and is listed as World Heritage of UNESCO since July 2008 within the site Cave of Altamira and Paleolithic Cave Art of Northern Spain.
The caves contain decorations in red ochre in the forms of hand stencils from as far back as 35,300 BC and dots. One red disk or dot has been dated to 40,800 years ago, making it the oldest dated cave decoration in the world as of 2012.
The caves are located along the Pas river in the Castillo mountain, squarely at the intersection of three valleys and near the coast. This is a fertile ground for agriculture, hunting and fishing, which explains the emergence of several prehistoric settlements there.