Another HDR photo from Flickr user: stuckincustoms.
I was a regional marketing manager for a large national bank in the late '90s and was responsible for the Chicago, New York and Washington, D.C. markets. Our office was right across the street from Grand Central on 42nd Street. Although I used Penn Station for my local travel, I would walk over to the main concourse and just watch all of the activity. I can just imagine what it was like in its heyday.
More information about Grand Central here.