At one point in the song one of the husbands says, "You know what comes to my mind every time I see him? The Seagram's Building!" Would a DL brethren or sistren kindly explain? TIA!
Perfect. But cold.
The Seagram Building (not "the Seagram's Building") is a stellar example of Mies van der Rohe's modernist design, apparently pure, stripped of ornament (again, only ostensibly; it's just a different sort of ornament), and dramatic against its surroundings (more so when it was built; now it's surrounded by modernist buildings, several of which are imitations of it).
Maybe the best explanation of what Sondheim meant is an analogy Paul Goldberger applied to the CBS building on 6th Avenue, comparing it to a duchess who finds herself at a rather sleazy party, and, in order to minimize the effect on her reputation, refuses to talk to anyone else there. Similarly, the beautiful Seagram building had nothing to do with its context, in which its presence served as sort of a reproach.
Its exterior is all smoked glass windows. You can't see into the building from the outside. Only those on the inside can see out of the windows.
Similarly, Robert is an inscrutable observer of life. He is trapped in his own "inside" looking out while no one outside of him can understand what's going on inside his mind.
Actually, R3, you CAN see inside, and the occupants of the offices near the windows are required to leave their lights on -- to say nothing of all of the lights being installed in a specific, pre-determined pattern to optimize the view inward at night.
Ah yes, R4, but like Robert, you can only see inside it when it's lit up. In the sober light of day it is opaque.