New designs and materials will make future skyscrapers sturdier, safer, and smarter.
The idea of building a tower to
touch the sky goes back thousands of years. And within the past century, architects and engineers have designed seemingly impossible structures that stand a quarter-mile high -- a tribute to humanity's need to test the limits, as well as a way to alleviate congestion in crowded cities. But after terrorists crashed two hijacked passenger planes into New York City's tallest buildings on September 11, leveling both of the Twin Towers, iconic skyscrapers around the world suddenly gained a new label: target.