Each tower had 40 huge steel columns running up the centre. If the
booms you can hear during the collapse were the floors hitting each
other and not demolition charges why were these steel columns not left
standing but found at the debris pile in uniform 30 foot lengths? Why
weren't those columns standing after the floors had suposedly 'slid
down' around them?

Here's one of the columns:
http://img225.imageshack.us/img225/2...dcolumnfy6.jpg


p.s. take rec.aviation out of your replies - they're only interested in
the plane part.