This tiny chapel was built in the mid-20th century to replace its 8th-century predecessor (erected by Pelayo's son Favila), which was destroyed during the Spanish Civil War. The 1940s rebuilders discovered that the mound the chapel sits on was an artificial one containing a 5000-year-old megalithic tomb; it's now visible beneath the chapel's floor. Visits are semi-guided in Spanish, English or French; enquire at the tourist office.