Several thousands people were murdered on September 11th, 2001, and I think they deserve an iron-clad theory that explains everything beyond any reasonable doubts. Rushing to conclusion is not a good way to honor them.
For nine years, I believed in the official explanation -- until someone presented me with the evidence and I took a hard look on it ... once I did that, I found many obvious doubts in the official explanation.
Among the doubts, the one surrounding Building 7 is the most obvious. On that fateful day, apart from the twin towers, this relatively unknown, 47-story, Building 7 of World Trade Center also collapsed. This building was NOT hit by any plane and had only a small-scale office fire, yet it collapsed in almost the same manner as the twin towers -- completely symmetrical and in an almost free-fall speed.
Please review 00:01:30-00:02:00 (30 seconds) of this video
"Architect Gage questions the official explanation of the collapse of World Trade Center"
From the video, we could see clearly that, at the moment of collapse, all the support of the building was gone simultaneously, which was not possible if fire was the cause of the structural damage -- the steel beams would not be melted all at the same time, if they would be melted ever (the temperature of office fire is not high enough to melt steel beams). The official explanation is very questionable and has been challenged by more than 1,500 architects and engineers, who think the building was taken down by controlled demolition (see http://AE911Truth.org)
If you still are not convinced, please see this other example. Pay attention to the footage of 00:00:32-00:00:50 (about 18 seconds. Note: the video has no sound)
"Controlled demolition examples"
Notice that in this video, there was a control demolition that was badly done -- where only part of the supporting structure was successfully taken down by explosives. A normal office fire can only achieve worse than this because fire can't take away all supporting structure of a building at the same time.
By comparing this footage to the perfect collapse of World Trade Center Building 7 (shown above), it is hard not to conclude that the WTC7 was taken down by a perfectly executed controlled demolition.
I detest conspiracy theory, and I think I am not spreading one. However, I think I have some curiosity and some insistence of justice. They make me think again and again on the above observation. I wish you will also spend some time thinking about it. Ask questions first, don't rush to any conclusion or explanation. I believe the solving of this mystery will be not too much unlike in many scientific discoveries, where observations often precede explanations by many years, if not decades.