Discovered in 1968, the cave here has 20,000-year-old paintings on a par with those in Lascaux, France, and Altamira. Giant horses and deer prance about the walls. To protect the paintings, no more than 375 visitors are allowed inside each day, so reservations are essential. The guided tour is in Spanish. There's also a museum of Asturian cave finds, open year-round.
Av. de Tito Bustillo s/n, Ribadesella, Asturias, 33560, Spain