World Trade Center 7, funnily enough. The idea of some government goons being like "I'm just worried this isn't dramatic enough, Americans just won't be upset enough by two towers going down, we probably need to randomly knock down a tower that nobody knows to really push them into a frenzy" is very curious to me.
That our government could have competently pulled that off.
In general most actual conspiracies are a consequence of trying to cover up incompetence more than malevolent enterprises. If there was a conspiracy related to 9 11 it would probably be far more banal than the grand theories - it would be something along the lines of "if intelligent operatives had bothered following up on a lead or keeping an eye on their sources they would have prevented it all and higher ups kept that secret".
