Obviously if we talking about the twin towers and not building seven given the talk of 'jet fuel'.  In these cases, the 'down' is suspicious but the 'up' is even more so.  That is to say, the shattered i-beams and debris velocities and trajectories as the 'collapse' occurred.

It's OK to go ahead and concede that the whole thing was probably a false flag operation performed in order to achieve a psychological impact on the citizens.  The 'catastrophic and catalyzing new Pearl Harbor' anticipated as necessary in the PNAC document not to long before the event (authored by Cheney, Rumsfeld, and co.)  The feeling of entertaining a hypothesis which nicely matches most or all of the observations is much more comfortable than trying to strain a hypothesis which just doesn't work (like the global climate change scammers are burdened with.)   Lots of nations have done such things over the years.  It's probably more common than not.

In hindsight, I am sort of seeing things as a struggle between the 'one-worlders' and the 'American century' crowd.  The former represented by Obama an the latter latter by Cheney.  As I study things more, I see the 'American century' path to be the lesser of two evils which makes me glad they pulled off 9/11.  I've always been in awe of Cheney for the audacity of the feat.  Even the PNAC document concedes that the 'new American century' would probably be the last time a multi-polar world was practical and we'll end up in a one-world system anyway.  In my mind there is no way that such a thing does NOT turn into a hideous totalitarian dictatorship from which there will be nowhere to run and hide.