Fall and Rise: The Story of 9/11: A gripping biography of triumph over tragedy

by Mitchell Zuckoff

the towers’ engineers designed each one essentially like a box within a box. The external walls, the outer boxes, were made entirely from thin bands of structural steel. Like the exoskeleton of a crab, those outer walls minimized the need for heavy, bulky internal steel support columns. The external columns gave the towers a look reminiscent of pinstripe power suits, but it was more than a stylistic choice. Fewer interior steel columns meant more rentable space on each acre-sized office floor. Some internal columns were still necessary, so the engineers clustered them in the inner boxes, known as the central core, among the elevators, stairwells, and utility shafts. The result was an extraordinary thirty thousand square feet of rentable, customizable space on nearly every office floor, uninterrupted by columns or walls, with incredible views to boot. Also, the narrow windows between the closely spaced exterior columns tended to reduce dizzying vertigo among people afraid of heights, which oddly enough included the architect, Minoru Yamasaki.