岩窟の聖母
During the twenty years that he held this post he was responsible for many important purchases, among them Leonardo da Vinci's "Virgin of the Rocks", Raphael's "Ansidei Madonna", Anthony van Dyck's "Equestrian portrait of Charles I", Hans Holbein the Younger's "Ambassadors", and the "Admiral Pulido Pareja", by Diego Velázquez (this subsequently attributed to Velázquez's assistant Juan Bautista Martínez del Mazo). He also added to the noted series of Early Italian pictures in the gallery. The number of acquisitions made to the collection during his period of office amounts to more than 500.