7 World Trade Center. Tower 7 was damaged during the collapse of the adjacent main towers, after which fires raged for several hours. Eventually, it collapsed. The conspiracy theory is that the building was destroyed using hidden explosives, much in the same way as the conspiracy holds for the main towers. The catch is that no one was in Tower 7 when it collapsed and no one was killed or injured during its collapse, making it a conspiracy to just destroy some barely significant New York real estate. Essentially, the point of the conspiracy is just that if it were not a conspiracy, then conspiracy theorists would be forced to admit the conspiracy surrounding the main towers is also less plausible.