This is the board for you if you wish to discuss or explore conspiracies of any kind, historical or current.
The way the towers were constructed, it is possible that even an office furniture fire on one of the floors, perhaps aided by an accelerant, could have brought down the south tower because the floor trusses were not adequately fire proofed and a truss is only as strong as its weakest support. The north tower might have taken a fire on two floors. Flying planes into the buildings probably was not necessary to bring them down, but the structural engineer who devised the plan probably thought they were. Also fairly obvious there were insiders involved given worded PA system announcement claiming that even though north tower was in flames, everything was safe in the south tower amd occupants should stay in the building. That was a key part of the plot. As for the other buildings, like seven, no doubt also cheaply built and collapsed from a domino effect.