- Narrator: [about WTC7] It had 81 columns, 57 columns around the edge, and 24 core columns inside.
- Richard Gage: In order for the perimeter to fall perfectly and symmetrically - which it pretty much does - all of those columns have to be removed within a tenth of a second. Fire cannot do that, controlled demolition can.
- Peter Hayden - Chief, NYPD: We had a discussion with one particular engineer there, and we asked him, if we allowed it to burn, could we anticipate a collapse, and if so, how soon? And it turned out that he was pretty much right on the money then. He said, "In its current state you have about five hours."
- Daniel Nigro - Chief, NYPD: It was like the surface of another planet. All there was, was powdered debris and metal. It was - a very strange scene.
- Daniel Nigro - Chief, NYPD: The biggest dicision was to make an evacuation zone around Number 7, to pull everyone away, to stop the rescue efforts that were going on, which was very difficult to do, because - there were people trapped, still, and we stepped back, we had to step back and wait.
- Narrator: At 5:21 PM, Tower 7 finally collapses. The 47-storey skyscraper and its contents are pulverized to dust.
- Richard Gage - Architect: A sixth-grader can look at this building falling at virtually free-fall speed, symmetrically and smoothly, and see that it is not a natural process.