Originally Posted by Rochard

The WTC towers were designed in the 1960s and completed in 1971. They were designed to withstand the crash of a plane of that time - not an airplane built forty years later.

No steel structured has ever collapsed like this? You think? With the exception of the Empire State building in the 1940s, no other skyscraper has ever had a large plane intentionally crashed into it! And the Empire State Building incident was completely different; The building is different, mostly concrete, and the plane was a 1940 bomber with little fuel in it.