Debunking the "truthies"
Structure Magazine explains one probable cause of the WTC 7 collapse. "Single Point of Failure: How the Loss of One Column May Have Led to the Collapse of WTC 7"
Conspiracy theorists say World Trade Center 7 is the best proof for controlled demolition because it wasn't hit by airliners and only had a few fires. They also claim that there was a confession from the building owner who said he "pulled" it. But this is deceptive because while building 7 wasn't hit by an airliner, it was hit by the large perimeter columns of the Tower collapse. It was 400 ft away but the towers were more than 1300 ft tall. As the tower peeled open, it easily tilted over to reach building 7. Below is evidence showing that conspiracy theorists are wrong.
As you can see from the graphic below, all the buildings just as far away from both towers as WTC7 were hit. The others were either very short buildings which didn't have to support a massive load above or had no fire. Only Building 7 had unfought fires and the massive load of 40 stories above them.
The second paragraph above has been challenged by conspiracy theorists. For more information on this and a rebuttal read the update around the middle of the page.
Below is a photo of the Bankers Trust building.
As you can see, the building never caught fire so it was never in any danger of collapse. It also was constructed differently, with a web column design. The interior columns were not pushed out to the perimeter.
Note the WTC columns laid out as if there were a path to the building. There are no concrete slabs attached to columns. This is yet another example of pancaking. With the floors pancaking straight down, the perimeter walls were free to lean over in tall sections before breaking off and coming down. That's what gave them distance.