What was the part of the Pentagon that was hit on 9-11 used for?

The Pentagon handles the military. On 9-10 one day before a plane crashed into the Pentagon, Donald Rumsfeld was questioned about the Pentagon not accounting for 25% of its spending over the recent years ($2.6 trillion). The audit wanted answers, but less than 24 hours later a plane hit the pentagon and the fires that resulted were in parts of the pentagon where the plane had not hit (which in itself is odd). So what parts of the Pentagon housing what type of paperwork was "hit" by the airplane or should I say caught on fire? (btw Those immediately interviewed said to reporters they heard and felt bombs going off all over the place and showed disbelief when they were told an airplane had hit the building). (No airplane was witnessed, or found btw it just "vaporized" lol and I got a bridge I can sell you)