One year I was shopping at the Barnes and Noble store that used to be in the Citibank Building the week before Thanksgiving and I saw Barbara, Clarke and crew unloading and setting the display up. It was great to see how it went together. It was all modular and went together with self aligning Coffin locks.
I got to take my then very young son to see it the last year. They all knew it was the last year it would be there. A bittersweet experience.
The Dunhams used to have a whole group of their layouts open to the public in a town near their studio. One of the layouts they showed there was the former Citibank layout. They even had and showed the 4th scene that had originally been part of the layout a homage to the 1939 Worlds Fair. It was replaced with the final winter scene. The attraction was called "Railroads on Parade" and it was in the town of Pottersville, New York right off the I-87 exit. My family stopped a few times on our way into the Adirondacks. We all really enjoyed it but noted it was often empty of other visitors. The NYC Hudson painting that Bob @RSJB18 showed was originally displayed on top of the front of the attraction.
There is another Dunham layout on public display in the Adirondacks at the North Creek Station Museum. It is in HO scale and of the D&H in North Creek.