NIST has come up with a very unsatisfactory explanation for the collapse of WTC7, basically saying it is the first such building to collapse entirely due to fire. This won't satisfy anybody, but the report came out so late nobody may notice. The irony is that the glaring inconsistency between the official explanation for the twin tower collapses and the new NIST report is unavailable to twin tower controlled-demolition theorists, who of course say that the plane crashes were insufficient to account for the building collapses. The standard view of all legitimate structural engineers, including the guy who actually designed the WTC, is that the towers fell as the airplanes knocked the insulation off the steel girders, insulation that was put there for the specific purpose of preventing a fire from weakening the strength of the girders to the extent that they could no longer fulfil their structural requirements. Of course, no planes hit WTC7, meaning the insulation should have remained intact. Since, in the view of the controlled-demolitionists, the planes are irrelevant, the inconsistency in the NIST explanations is not available to them.