While in Burgos, pilgrims can make the most of their stop and visit a scenery that is unique in Spain. Ojo de Guareña contains the vastest extension of caves in Spain, and one of the world´s most important. They cover a total area of approximately 100 km. In the interior of these caverns can be found invertebrates species that cannot be found anywhere else.
Ojo de Guareña is a Karstic formation situated on the south slope of the Cantabrian Range, where stands a rocky cut composed of limestones and dolomites, over an impermeable substratum of marls and argillaceous limestones. The characteristic caves were hollowed out by the Guareña and Trema rivers, whose waters leaked into the big rock during the Upper Cretaceous period.
This spectacular scenery is home to beeches and birches in the north, and holm oaks and gall oaks in the south. The vegetation inside the caves includes algae, fungi and bacteria.
This Nature Monument is inhabited by a variety of birds of prey including vultures and Egyptian vultures. The forest is home to foxes, wild boars and wildcats. But the most interesting fauna is found inside the caves, more than 50 species of invertebrates, four of which are quite unique.
The historical aspect adds to the biological and geomorphological values of Ojo Guareña. The caves contain several Prehistorical sites that allow to follow the evolution of human religiosity -from the Paleolithic to the present- in great detail. The Hall of the Tracks show the footprints made by our ancestors approximately 15,000 years ago.