Building collapse? Not sure. The Urban M0ving Systems things is very weird. The bombs they found in the base are also indicative of a much larger plot than just the airplanes. Connections to multiple governments "friendly" to the US is also not great. Anthrax scares and Iraq were also clumsily connected to it.

Denver airport, what about it? Weird artwork? Supposed hidden structures? I dunno. The runways are much longer because of air density and how hot it gets there in the summer.