This 11C church was one of the first examples of Romanesque architecture in Spain. A crypt was built to support the edifice although it gives the impression of being older given its massive structure and ancient appearance. The west doorway (12C), the Porta Speciosa, takes its name from its wealth of sculpted decor. The interior boasts several interesting artefacts, including a wooden box containing the remains of the first kings of Navarra.