The Chapterhouse archives are installed above two naves of the Cloister and are open to researchers. Entrance is through the chapel of Saint Lucia in the Cloister.
This important center is responsible for safeguarding various papyruses (5th-8th centuries), approximately 200 codices (the oldest dating from the 8th century), hundreds of incunables, over 40,000 parchments (9th-13th century) and a voluminous collection of documents from the institutions which have been at the Cathedral over the centuries, as well as from some other entities and individuals. Of particular interest is the Esponsales collection, which goes from 1451 to 1905 and contains hundreds of thousands of names of people located within the geographical confines of the ancient bishopric of Barcelona, and constitutes an excellent source for genealogical and social studies.