You can’t tell from the black and white photographs, but the O.V. Catto school would have been green in color. It was built with green serpentine facing stone, a local stone still seen at College Hall on the University of Pennsylvania campus, which was built 5 years earlier than the Catto school. I should note that College Hall’s stone has had many campaigns of repairs and that much of the green you see is a cement-based stone patching material!
UPenn-College-Hall_Serpentine