Collegiate Church (XII - XIV century). Data from the second half of the twelfth century, but was recnstruida mostly in the fourteenth century. Is transitional Romanesque or Romanesque-arched influenced as they were Cistercian monks of the Cistercian Order who lived in the Monastery of Oia which finished construction. Collegiate being instituted in the year 1484 by Bishop D. Diego de Muros. It is a Latin cross basilica with three naves. The main altar is Baroque (1726). The main façade has a portico formed by three arches that shelter a door with three semicircular archivolts ornamental leaves.