East of Cangas just off AS-114 is Cuevo (Cave) El Buxo wherein you may see Neanderthal cave drawings.  A local women is your guide.  She does not speak English. Also, only about 25 people per day may see the cave.  
Plan to stay overnight in Cangas de Onis and arrive early the next morning to be assured a viewing.  The elderly woman (left photo) was so excited that we were going to the cave.  She had lived in the area all her years and had never seen the inside of the cave or its rare art.  (Next)