The buildings were steel structures, a steel structure cannot pancake on itself floor by floor in less than 10 seconds that is a physical impossibility. The New York Firefighters that were on the scene confirmed they heard explosives and that it was if it were a controlled demolition. Building 7 went down like a controlled demolition, no fire would cause a building to collapse on itself in that manner. A Scientist have discovered traces of explosives that were used to place within the buildings to cause a controlled demolition. Besides Airplane fuel does not cause a steel building to collapse and fall on itself. The twin towers were designed for emergency airplane collisions.