Matt , One of the biggest smoking guns of 9/11 was the way World Trade Center Building 7 collapsed at free fall speed almost straight down in its own footing . NIST made some statements that were just ridiculous about the office fires playing a part in builing 7 falling along with what they said about 1 column that supposedly weakened the structure . The Engineers and Architects have let themselves be heard about what can and can't happen to a Steel & Concrete building . Until 9/11/2001 , not one Steel & Concrete building ever collapsed due to fire . On 9/11 , World Trade Centers 1 , 2, and 7 all collapsed .