For me the highlights of the actual collection were the Pop Art pictures and the huge Richard Serra Sculpture/Installation 'The Matter of Time'. Made from large sheets of thick corten steel, bent in compound curves, it plays very successfully with the subjective experience of time. The series of spirals seem to take far longer to enter than they do to exit even though you are retracing your steps. See Here and scroll down. It's a perfect compliment to the building itself.