The walls are not straight. Most buildings have flat sides, except for maybe an alcove, or some rounding on the fancy brick ones.
This one is completly wavy, like the way a skirt might drape (not the straight skirts, the billowy ones).
If you ever walk the Brooklyn Bridge, you can see it to the left, as you head towards manhattan (or you can check the article on the NY Times website (its called the Gehry Towers)