The September 11, 2001 collapse of the Salomon Building, or WTC 7 was an atypical controlled demolition where the idea is to start by crossing your fingers and aiming a carefully measured amount of flaming debris from a much taller nearby collapsing hi-rise you've just bombed toward a smaller building with a precise quantity of directional charges so that you damage it just severely enough while starting major, uncontrolled fires on multiple floors as a cover for a later implosion of the lower building with high explosives or incendiaries. You evacuate everyone inside who hasn't already left, establish a safety zone around the targeted building, and set up a transit to monitor its movement as it slowly degrades structurally for six hours or more from the fires. When you finally "pull it," a catchy new demolition term coined by Larry Silverstein, the long-term lessee of the World Trade Center, and the FDNY to mean "blow up some guy's modern, almost fully-occupied 15 year-old hi-rise so that he can confess publicly to it later and still collect $861 million in insurance from a dozen different companies to pay off his creditors and rebuild while receiving no income from it for years" the targeted building falls asymmetrically and leaves 12 stories on the north side standing, which, by sheer coincidence in this case, is the side that wasn't hit by the falling debris you carefully aimed at it almost seven hours previously. You should always use very quiet high explosives that no one can hear from more than a block away, and randomly detonate them hours before the actual collapse, or you can use thermate, but whatever you choose, it must be the type which leaves no evidence on the column ends or any other piece of structural steel in the debris pile afterward, and is unaffected by the fires. This is a very unusual controlled demolition technique which has only recently been discovered by alert members of the 9/11 "truth" movement. It's highly effective if the debris from the higher building falls exactly where you intended, which it has done every time so far.