The Sanctuary of St Michael of Aralar hides a jewel: a gold and enamel gilded altar and a priceless example of European Romanesque gold-work thought to have come from a workshop in the French Limousine region around the end of the 12C. This artefact was discovered in the 18C in the small Romanesque chapel, part of the church built over many periods. Part of the walls and the apse are 9C Visigoth, while the rest is pre-Romanesque (10C).