The monumental cathedral and its attached museum glitter with the gold that attests to the great wealth the Camino has bestowed on otherwise backwater towns. An audio guide to the cathedral and its treasures is €1. Construction was begun in 1040 by Santo Domingo de la Calzada, who also built a bridge, hospital and pilgrims' hostel; he is buried in the cathedral.
The cathedral’s most eccentric feature is the live white rooster and hen that forage in a glass-fronted cage opposite the entrance to the crypt (look up!), which have been changed every 15 days since 1350. Their presence celebrates a long-standing legend, the Miracle of the Rooster, which tells of a young man who was unfairly executed only to recover miraculously, while the broiled cock and hen on the plate of his judge suddenly leapt up and chickened off, fully fledged.