It is of great geological beauty and is over four kilometres in length; it is considered to be the sixth cave in the world of its type. Excavated in an area of puddingstone cemented with limestone motifs from the Oligocene deposited 35 million years ago, it is located near the hamlet of Puras de Villafranca. In its lower part a river runs through the cave. This beautiful place with numerous formations, towers, helictites, outflows, stalactites, stalagmites, and columns left by lithogenesis on its floors, ceilings, and walls is one of the world’s top caves. It surprises us with three superimposed storeys, the top two of which contain the most magnificent and most outstanding formations with their grandeur and geological originality.