The origins of San Martiño de Mondoñedo can be found in the early Middle Ages. However, an endless documentary dossier complicates its study. What we do know is about the existence of a primitive construction from the 10th century, from which we can find some remains today. Some theories defend that the origins of the Episcopal see of Mondoñedo are indeed in this monastery, home of the current museum.
The present building belongs to Romanesque architecture - from the end of 11th century. Some elements are posterior, such as the 18th century buttress. The decorative sculptures are extremely interesting, due to their style and iconography - given that both of them reflect an art typical for the Pilgrimage Ways.
The church of the monastery (today parish church) hosts a wide collection, noteworthy the altar's façade with the Cristo en Maxestade from the 12th century. Also remarkable, the staff and ring of the bishop Gonzalo, along with sculptures, paintings, documents, reliquaries, missals and a collection of goblets - all of this religious pieces.