We walked over by number Seven World Trade Center as it was burning and saw this 40-plus story building with fire on nearly all floors. –FDNY Lieutenant Robert LaRocca

Just when you thought it was over, you're walking by this building and you're hearing this building creak and fully involved in flames. It's like, is it coming down next? Sure enough, about a half an hour later it came down.

The biggest decision we had to make was to clear the area and create a collapse zone around the severely damaged [WTC 7] building. A number of fire officers and companies assessed the damage to the building. The appraisals indicated that the building’s integrity was in serious doubt.

The fact that a Spanish skyscraper is still standing after an intense
fire consumed the steel and concrete tower for 24 hours provides real
world evidence that fire alone does not cause high-rise towers to
collapse.

Owner's Admission?
Silverstein's Apparent Admission that Building 7 was Demolished
'Pull it' as Demolition Admission
Silverstein apparently admitted that the building was deliberately demolished by the New York City Fire Department late in the afternoon.
Silverstein's alleded admission consists of his following on-camera statements shown in America Rebuilds.
What does Silverstein mean by "the decision to pull" Building 7? Many observers have suggested that a later passage in the same documentary indicates that, in this context, "pull" means to destroy a building through controlled demolition. In preparation for the controlled demolition of irreparably damaged Building 6, a Ground Zero worker says
... we're getting ready to pull the Building Six.
An alternative explanation for Silverstein's remark is that he was referring to a decision to "pull" firefighting operations in Building 7. That explanation is advanced in a September 9, 2005 statement issued by Stilverstein Properties spokesperson Mr. Dara McQuillan:
Seven World Trade Center collapsed at 5:20 p.m. on September 11, 2001, after burning for seven hours. There were no casualties, thanks to the heroism of the Fire Department and the work of Silverstein Properties employees who evacuated tenants from the building.
A more sophisticated interpretation of Silverstein's comment is that it is bait, eliciting the widespread circulation of an interpretation that is easily denied if not refuted. While failing to provide substantial evidence for the controlled demolition of WTC 7, the story has functioned to eclipse the overwhelming case for demolition based on the physical characteristics of the collapse documented in photographs and videos of the event and the rubble pile that resulted. Those visual documents establish that the building's collapse was an implosion exhibiting all of the features of a standard controlled demolition, including:
• Very rapid speed of fall
• Symmetric collapse around its vertical axis
• Production of large quantities of dust
• Collapse into a small, consolidated rubble pile, with exterior walls lying on top

Larry Silverstein, WTC 7,
and the 9/11 Demolition
9/11/2001 radio broadcast: "We were just sitting here watching all the smoke pouring up from
number 7 ... we really couldn't see much damage on it ... I turned in time to see what looked like a skyscraper implosion, it looked like it had been done by a demolition crew ... that's number 1,
number 2, and now number 7 that have come down from this explosion and folks just simply can't believe it. ... I just never for the life of me imagined that these huge buildings would just fall, and that's what happened, they just crumbled." [338kB wma download]

Larry Silverstein, the controller of the destroyed WTC complex, stated plainly in a PBS documentary that he and the FDNY decided jointly to demolish WTC 7 late in the afternoon of 9/11. In the documentary "America Rebuilds", aired September 2002, Silverstein makes the following statement;

"I remember getting a call from the, er, fire department commander, telling me that they were not sure they were gonna be able to contain the fire, and I said, 'We've had such terrible loss of life, maybe the smartest thing to do is pull it.' And they made that decision to pull and we watched the building collapse." [wmv download]
In the same program a cleanup worker referred to the demolition of WTC 6: "... we're getting ready to pull the building six." [wmv download]
There can be little doubt as to how the word "pull" is being used in this context.
The building fire alarm system [for WTC 7] was placed on TEST for a period of 8 h beginning at 6:47:03 a.m. on September 11, 2001. Ordinarily, this is requested when maintenance or other testing is being performed on the system, so that any alarms that are received from the system are considered the result of the maintenance or testing and are ignored. [NIST]
An explosion occurred in WTC 7 prior to the collapse of the twin towers:
After the initial blast [Flight 11 hitting WTC 1], Housing Authority worker Barry Jennings, 46, reported to a command center on the 23rd floor of 7 World Trade Center. He was with Michael Hess, the city's corporation counsel, when they felt and heard another explosion. First calling for help, they scrambled downstairs to the lobby, or what was left of it. "I looked around, the lobby was gone. It looked like hell," Jennings said. [Traverse City Record Eagle 9/11/2001]

Barry Jennings "We started walking down to the eighth floor. Big Explosion. Blew us back into the eighth floor." - Barry Jennings on 9/11 news video.