I lived in Washington, DC on 9-11. A couple of days later I drove down Route 110, which skirts the Pentagon and runs between the building itself and the employee parking lots. They had been pulling wreckage of the plane out of the building, and carting it to a specific section of one parking lot via a flyover ramp that runs over 110.
I saw twisted parts of the plane, and I looked at them hard (even though I was driving and that was dangerous, duh), and I will never forget it. The largest piece was about the size of a school bus. It had the blue and red lettering of the airline on the outside.
If they wanted to fake a plane crash, fine, I get that there are false flags all the time. But would they have gone to such trouble in this case, to put humongous twisted pieces of metal painted with the airline's color-scheme in that parking lot? I've never been able to buy into the "no plane hit the Pentagon" theory for this reason.
FWIW.