Located in the Romanesque Church of Santa María de Sar, this small museum, founded in 1975, houses pieces of very important historical and documental value, such as the church's foundational parchment, dated 1136 and bearing the seal of Archbishop Diego Gelmírez. The section dedicated to gold and silver articles includes liturgical objects made in Compostela's workshops during the 18th century. The archaeological section consists of a series of pieces from the old Romanesque cloister, the work of Master Mateo or his school.