This is one of the most quintessential buildings of the Spanish Romanesque. It was built by Doña Mayor, the widow of Sancho Mayor, King of Navarre, and has been the spiritual resting place of the pilgrims on the road to Santiago.

The building features three naves, all with barrel vaults and rib arches. There are three circular apses in the sanctuary, and the transept has a polygonal dome. The capitals of the columns are exceptionally lovely and are profusely decorated with vegetation and iconographic motifs. The two circular towers flanking the entrance door on the facade are a new development reminiscent of the German style. On the interior there is a Crucified Christ of exceptional value.