[WhiteGuy]

WTC-7 was unharmed by an airplane and had only minor fires on the seventh and twelfth floors of this 47-story steel building yet it collapsed in less than 10 seconds.

So..............

What caused this building to collpse?

Serious question, I don't know, what caused a 42 story building to collapse?

[roylene]

All I can tell you is this, my husband is an engineer, he marveled (thinking the terrorist actually knew what they were doing) at the brilliance of hitting the buildings where they did, with a plane full of fuel. He went on in detail about the physics involved, I think my eyes glazed over after a few minutes. If I can remember in a nut shell the planes hit, fuel caused great heat and the buildings began to collapses under their own weight.

[xkaydet65]

I believe WTC 7 was the site for the very large diesel generators that would power NYC's emergency response center on its 23rd floor. Fires from the Towers ignited the huge diesel resevoirs and weakened the structure as did the impact of two skyscraper collapses. I saw WTC 7 go down in the late afternoon of 9/11 after FDNY concluded its fires too out of control to attack.