Well, if you're being pedantic, I think we've proven that there was actually a series of blasts or detonations centred on the central columns of the 3 buildings causing them to "free-fall".
How thick are you bassas, The twin towers had a kerosene heating system! flowing through pipes in each of its floors and had 10,000 litre tanks every 50 ft to store the stuff. I am sure the intell of Al Queada knew this, good job yous dont try to become terrorists! Easy to find out!
Hitler has only got one ball Himmler has 2 but they are small Bormann has there just big hole But Goebbels has no balls at all
The buildings didn't "free fall" though, it looked very much like a controlled demolition but the delay in the building collaspe proved that it wasn't.