9/11:Israel did it
When an event occurs that that fundamentally changes the dynamics of global geopolitics, there is one question above all others whose answer will most assuredly point to its perpetrators. That question is "Cui bono?". If those so indicted are in addition found to have had both motive and means then, as they say in the US, it's pretty much a slam-dunk.
And so it is with the events of 9/11.
Discounting the 'Official narrative' as the absurdity it so clearly is, there are just two organisations on the entire planet with the expertise, assets, access and political protection necessary to have both executed 9/11 and effected its cover-up to date (ie the means). Both are Intelligence Agencies - the CIA and Israel's Mossad - but only one had a compelling motive - Mossad. That motive dovetailed perfectly with the Neocon PNAC agenda, with it's explicitly stated need for "...a catastrophic and catalyzing event - like a new Pearl Harbor"  in order to mobilise US public opinion for already planned wars, the effects of which would be to destroy Israel's enemies.
This article marshals evidence for the proposition that "Israel did it".