sentences:  The cathedral museum, located in the sacristies, houses a large number of works of art, among which the portrait of the knight Don Garci Báñez de Muxica by El Greco and the chalice and paten of Saint Secundus.But it most notable work is the enormous processional monstrance (1571), a shrine in six bodies by the goldsmith Juan de Arphe y Villafañe.Its main theme is the "Sacrifice of Isaac".