There were a lot of folks I knew working the Pentagon, but that was in the 80s and early 90s before my departure. They were in the Comm Center in the basement. Now granted, this was some years ago, but there are still a lot of younger folks I trained over the years who are likely still serving today, whether as a military service member or as a GS civilian, and it’s a small world, with the militaries even smaller -- and the Signal Corps being smaller still. I couldn’t name most of these people today if my life depended on it, but I know I would recognize a lot of them if I saw them written down.
high res .PDF file
From “The Pentagon” at dtic.mil/ref.

Also, “The Pentagon Project” (just a little light reading).

Just a note here. Striking the Pentagon was not a crippling blow to the militaries. Each post, camp, base, and fort is a self-contained, fully functional command center, capable of carrying on the defense of this nation. Some are small and would require support from other local commands, but we do remain strong as a united force in this time of tragedy.

Dan