I would agree that there was a conspiracy by some who had appropriate warnings of 9/11 and chose not to respond to the forthcoming 9/11 attack (in order to make millions on investments), though there is no general agreement on what kind of conspiracy this was. I think one should follow the money. That said, don't be convinced by weak arguments, as they will delegitimize conspiracy claims. One of those weak arguments is to compare ANY tall steel structure with the WTC. Unlike the Windsor Tower, each WTC building was essentially a tube of massive steel beams around the outside, with relatively light-weight flooring between them. One should think about what was required for those outer beams to bend and break, which is another discussion. But the collapse of the inner floors in the 9/11 circumstances is fairly unacademic and easy to understand when one knows that they were not significant structural parts of the building. Look also at the Windsor Tower and its beams, which form traditional boxes of the same metal density throughout the structure. Hence the contents of those boxes could burn to a crisp while the boxes remained.