On 9/11/01 I was on the phone with family, who had a structural engineer visiting from overseas. She predicted the collapse and the manner thereof based on her assessment of visible crash damage.
Because of this I was forever immunized against competing theories, especially those which would require wiring up explosives when nobody was looking in buildings that were occupied to some extent around the clock.
(Phillipe Petit would not have been able to pull off his stunt if the buildings were actually completed and fully rented. They were still under interior construction and even then had security guards walking around. Imagine a team of demo guys running around under those conditions!
https://en.wikipedia.org/wiki/The_Walk_%282015_film%29 )