using aluminum and dble- paned insulating glass, it would span 16,000 square feet-- more than a third of an re-- culminating in a public space unique in architecture. and it would receive light in a selective fashion, to illumine but protect the artwork within, filtering out direct sunlight and e ultraviolet rays that could damage the art inside. by november of 1977, they were ready to receive the first of the commissioned works. they came from england, france, spain, and from across america: calder and moore, arp, caro, miro, motherll, rosati, their works to be placed in the grand spaces. ( orchestral music this building is a gift given to the natn by pl mellon, ailsa mellon bruce, and the andrew w. mellon foundation, but it is more than that. it is a statement, as one critic wrote, "of perseverance and excellence, against which all buildings and builders must now be measured."