Why did WTC7 collapse?

I don't generally go in for conspiracy theories, but one thing surrounding the 9/11 attacks has always bothered me.

Scenario 1: the official story

A bunch of muslim extremists hijacked four planes. Two were flown into the twin towers and one into the pentagon. The fourth was brought down by passengers before it could reach its target and crashed into a field in Pennsylvania. The damage from the impacts and the heat of the fires weakened the twin towers to the point where they collapsed. Two other WTC buildings also collapsed, weakened by fire and damage from rubble.

Scenario 2: the uber-conspiracy

Someone (maybe muslims, maybe not) organised by the US, hijacked planes. The bosses arranged for them to disappear from air traffic control, prompting the suspicion of terror that lead to all aircraft being grounded. The planes were flown to a US airbase, where all the passengers were transferred onto one plane. The planes took off again and two went and hit the twin towers. Meanwhile a missile disguised as an aircraft was fired at the pentagon and the plane full of passengers deliberately crashed into the pennsylvania countryside. The fourth plane was presumably hidden somewhere.

Back at the twin towers, the aircraft impacts didn't bring the towers down, so the bosses pressed the buttons to detonate the explosives that had been previously planted in all the WTC buildings, bringing them all down in controlled demolitions.

Which scenario do you think is more likely?

This is, after all, the US government administration we are talking about here. Dubya and friends. They took ages to find Saddam Hussein, still can't roust out all Iraqi insurgents, still haven't found Osama bin Laden, and quite frankly, I don't think they could find their ass with two hands and a map. How the hell could they have pulled off something like that?

And the key issue for me - how could they have done it with nobody knowing. If you think about the number of people who had to have some knowledge of that kind of thing - painting the drones, transferring the people and so on ... how can none of them have talked?

That's the big clincher for why scenario 1 just seems more plausible - you just can't shut up that many people (nor can you kill them all without people noticing).

The one thing that I don't understand is the collapse of the towers themselves. They imploded in near freefall time, looking exactly like a controlled demolition. Not only that but two of the WTC buildings were hit by aircraft, but four of them collapsed exactly the same way.

No high-rise building on Earth has ever collapsed due to fire. Ever. And some of the fires have been much more extensive than the fires in the WTC buildings, covered a larger area and burned longer and hotter.

OK, I grant you that the damage done by the planes and the addition of the jet fuel could have made things worse - maybe worse enough to bring down the buildings. I'd probably accept that if it wasn't for the strange way the buildings fell - imploding in pretty close to freefall time, looking exactly like a controlled demolition. I know from watching documentaries that a lot of work goes into calculating exactly how to place the explosives to bring a building down properly. Get it wrong and the building goes sideways or everywhere else. It's a very precise thing. How did two very different aircraft impacts near the top of the towers manage to have precisely the same effect as a carefully set up controlled demolition?

But OK, let's just say that is what happened to WTC1, 2 & 6 - they collapsed due to fire.

That doesn't explain what happened to WTC 7, which also collapsed that afternoon, and which DIDN'T have a 767 flown into it. It was also furthest away from the twin towers, and least damaged by them. This is in contrast to WTC 5 & 6, which were much closer and were significantly damaged by debris from the twin towers. WTC5 in particular had extensive fires, worse than any of the other buildings including the twin towers, but it didn't collapse.

I just don't get it. What the hell happened to WTC7?