The superimposed Isturitz Cave and Oxocelhaya Cave below it are abandoned underground beds of the Arberoue River. The Neanderthals and Cro-Magnons left their treasures in these cathedrals of limestone, full of monumental columns and majestic hangings. Everyday objects and works of art were found in the first cave, including three superimposed reindeer and a horse carved on a pilar. The chambers in the second cave are decorated with natural rock concretions and two reproductions illustrating the thirty drawings found on the walls.