Hallways, conference rooms, shops (there is a small mall in the Pentagon), more hallways, bunkers, monuments / military museums, and a bunch of other general use areas.
It's important to keep in mind that when the Pentagon was built, a computer was a person who did calculations and documents were sent to the secretarial pool to be typed; so the number and roles of its occupants were quite different. The space has been re-purposed over the past 70 years.
It's a very interesting building. You can tell that it was made with a focus on people walking from place to place. I think there are tours open to the public (but require a reservation). I'm pretty sure it's the only tour in the U.S. that features a Marine walking backwards for over a mile. I think there are over 15 miles of hallways in the Pentagon. There are 5 levels with 5 rings each, so you can imagine that's a lot of places to walk.
One of the things that isn't so nice now is the anti-radiation film that got placed on the windows after 9/11. The film is bright yellow, so everything that sunlight touches has kind of a gross pee colored tinge to it.
> The Pentegon [sic; Pentagon] is not under market pressure to be efficient or turn a profit. They don't even get audited.
The GAO [1] does something close to auditing - although the Pentagon's financial statements aren't in the kind of shape that they even can be audited (something the GAO and DOD are working on). [2]
Human Scale has a different meaning in art and architecture than it does in scientific fields. In architecture, it simply means that the building is designed to fit well with the human senses.
I find, for example, the Grand Arche uplifting. Tagging an architecture as not "human scale" seems to me an attempt to pit it against human aspirations.
Proposed Appleplex: 1.4 mil sq ft (?), 12-13k employees
Pentagon: 6.5 mil sq ft (3.7 mil for offices), 26k employees
Empire State Building: 2.8 mil sq ft, 21k (?) employees