I had a friend driving into work that day, and he saw the plane fly overhead as he was driving into work (he was late coming into the pentagon... granted he was always late lol)
Now granted I've seen it pretty close and have seen no plane but there are just too many EYE witness accounts of watching the plane come in.
The head of my organization is now deceased due to this incident along with many other people (I wasn't working for this group at the time but a different nearby)
Also dont forget that the area hit was recently renovated, with steel reinforced walls, especially the outer walls. The renovated area is actually pretty nice, although it reminds me more of a mall than a military place like the rest of it

lol
It happened, no question about it.