content: If a single floor starts to fall, pancaking is basically the only thing that can happen. The towers were a central core spire, and an outer wall support, connected to each-other with horizontal trusses. There were literally no other vertical supports between the core and the outer wall, and [spoiler alert], horizontal trusses don't hold vertical impact particularly well. You can even see in many videos the core still partially standing for a brief moment, the floors around it having been sheared away. I guess, ironically, that would make them that much easier to rig for demolition in the case of a false flag, since you'd only need to rig a single floor for failure, but it also makes the simple explanation of a plane hitting it work.