In 1227, Saint Ferdinand III decided to undertake the building of a Cathedral. Building continued until the end of the 15C and so all the stages of Spanish Gothic appear in it. The richness of the carved decoration and the collection of works of art make it an excellent religious museum. Be sure to see the magnificent stalls of the Choir, the Sacristy and its large collection of El Greco canvases and then the treasury and its splendid monstrance.