Slender towers rise to dizzying heights

In New York City, there's no escaping the pressure to be taller and thinner - not even for the skyscrapers.

Changes in building technology and materials in recent years have made it possible to build slender towers that are among the tallest in the world. And some of these cloud-puncturing beanstalks are poised to transform the city's iconic skyline.

So far, the thinnest of all is the recently completed apartment tower at 432 Park Ave. The stark white pillar, just south of Central Park, is 426 meters tall, but each side is only about 28 meters wide.