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 caves are located along the Pas river in the Castillo mountain, squarely at the intersection of three valleys and near the coast.

The El Castillo cave contains decorations in red ochre in the forms of hand stencils dated to about 35,000.

[1] The Cave of El Castillo was discovered in 1903 by Hermilio Alcalde del Río.

The paintings in this cave date to the Magdalenian, about 13,000 years ago, depicting horses, goats, bears, bison and reindeer.