As is well known, building 7 of the World Trade Center was not hit by an airplane, despite which it collapsed after the two main towers, supposedly due to a fire. The 47-story, 186-meter-high building collapsed in on itself in just seven seconds. Never before has a skyscraper collapsed in a fire. But it turns out that September 11, 2001, was precisely what happened, and with no less than three huge, modern and robust buildings, in a span of little more than seven hours. And I repeat, building 7 had not been subject to an impact of any kind, and had only a couple of fire sources on two different floors, with a perfectly controllable appearance for any fire-fighting system, reinforced by the immediate action of a large number of New York City fire contingent. Its sudden and almost instantaneous collapse, in free fall, perfectly vertical, in just seven seconds, for an architectural giant almost 200 meters high, is absolutely inexplicable if the hypothesis of an ultra-professional controlled demolition work is ruled out. Due to the size of the building, such work, according to the experts, could not have been less than a week in duration, carried out only at night, since the offices were in service during the day. Incidentally, the same must have happened in the two main towers, with the difference that the preparatory task in their case must have been considerably longer, since their height, 415 meters, was more than double that the one in building 7.