From Wikipedia... http://en.wikipedia.org/wiki/7_World_Trade_Center <div class='quotetop'>QUOTE("Wikipedia")</div> Here's the NIST report. http://wtc.nist.gov/pubs/WTC%20Part%20IIC%...pse%20Final.pdf I know your www.wtc7.net site poo poos it, but I find a reasoned explaination in the NIST report showing a huge gash in the corner of the buidling (page 17). The portion of the gash that is visible in this photo is at least 10 stories tall and 30 - 40 feet deep. You can then go to page 31 and see the beginning of an explanation of how a failure of a column in the south end of the building could cause the vertical falling of the rest of the building. Basically, the collapse of a portion of the tower would pull laterally on one or more floors, causing the splices in the rest of the columns of the building to fail, thereby causing the remainder of the building to fall vertically. You have to realize that the vertical columns in the building were not 47 story tall pieces of steel, but rather 25 or so steel columns that were spliced together. If you pull all the splices at say the 10th floor all to the south, the splices will bend and fail, causing 37 floors above to crumple down on them. But what do you get from the wtc7.net site to refute? <div class='quotetop'>QUOTE("wtc7.net")</div> As if the building was some solid rigid structure, like a tree toppling to a logger's axe. Steel buildings are more like houses of cards. Yank on a supporting layer near the bottom, and the layers above will come crashing down on top of it.