It is in Valbuena de Duero, looking at the monastery where Brother Diego's Cave is located, great and endless legends are in charge of describing this resource, specifically that of Brother Diego, for which different characters were buried in the 16th century, Among which is the protagonist Juan de Vivar (Brother Diego), whom the monks were in charge of supporting, thus giving him a stay in this cave where he lived in absolute tranquility, and thus helping the local shepherds with his medical studies.

The breadth of the cave allowed the new countrymen of Valbuena to set up tables for their lunches, and to spend a pleasant day in the coolness of the limestone.