Cistercian monastery, made up of a church, chapterhouse, side chapels, baptistry, gatehouse, three cloisters, refectory and kitchen, founded by King Alfonso VII at the beginning of the 11th century, completely renovated in the 17th, the reason why Baroque style is predominant. Inside, it conserves the original Romanesque church on a Latin-cross ground plan, large-sized single aisle above which there is a spectacular octagonal cupola, showing Italian influences. Sanctuary with a large, rectangular main chapel, with the ambulatory framed by two shallow, rectangular chapels. The octagonal cupola-cimborio is especially noteworthy, with windows in the huge coffered, barrel vault. On the outside, walls of large granite blocks. Depth of volume, with different structures adjoining the central one. Original main facade with chequered decoration by means of granite and slate bondstones, framed by four Corinthian order pilasters and columns, decorated with triglyphs and metopes, reaching up to the cornice, above which there is one impressive bell tower (the other no longer exists). At the main altar, Gothic tombs from the 15th C., in granite, of the Andrade family (medieval lords), with the wild boar, the family emblem. Stone retable in Baroque style dedicated to the Virgen de la Cela. Three cloisters, the best conserved is the processional cloister, in Renaissance style with a stellar vault and Baroque fountain in the centre of the patio; part of the gatehouse cloister is conserved together with the eastern or dormitory cloister, in rubblework (very deteriorated). The whole construction conserves the outer walls, perimeter wall, interior fountain and another external fountain; the rest of the structure is in ruins.