|Anatomy of a collapse
View how the North or the South Tower collapsed. Also, view the attack on the Pentagon.
A quarter of a mile high, the 110-story World Trade Center towers were the tallest in the world when they were completed almost 30 years ago. Designed as huge steel tubes, the towers were supported by closely spaced, 14-inch steel columns on the exterior aided by steel columns in the central core. Their collapse almost certainly was caused more by the heat generated by thousands of gallons of burning fuel than by the impact of the jetliners.
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GRAPHICS BY STEPHEN ROUNTREE AND DOUG STERN - USN&WR
REPORTING BY AVERY COMAROW, DAVID LAGESSE, AND KENNETH TERRELL-USN&WR