Building 7 was hit by no aircraft or debris. It had several small fires and amazingly collapsed in symmetrical fashion at free fall speeds. We saw in Madrid a building burn at intense levels for MANY hours but not collapse. Is there any scientific explanation for such a catastrophic structural failure in a largely steel building? I am concerned. Friends and family work in similar structures. It seems strange that I see little debate on such an important subject...a modern steel structure completely collapsing after a few small fires ignite. I have read the official reports. They summize they cannot explain the collapse. Does anyone know of any other reports that could shed some light on such an important subject? Does anyone here have a view on how steel could collapse in such a sudden, catastrophic manner?