What the World Trade Center Building Designers Said: Before and After 9/11 (tags)
For a long time its been assumed that the WTC was designed to withstand a 707 flying into it at a low speed. But its now been confirmed that the original design was made to withstand a plane flying at 600 MPH.
Someone told me that the final NIST Fire Report for WTC2 reads like the structural engineer's version of The Emperor's New Clothes! So I had a look at the report, and found it described pressure pulses, smoke and/or dust screens, large pieces of debris ejected at high velocity, extremely radiant molten metal flows, and other correlated unusual behaviors. Here is a closeup view that you probably haven't seen. (text and video extracts)