Adventures in Architecture; Aqua Tower in Chicago

[....The Aqua Tower, rising up in a dance of ever-changing concrete forms, is very different from its neighbours. Seen from the sidewalk, it really does have the look of a multi-layered Lake Michigan rock formation, albeit one that towers above the city. This is a Chicago landmark that has broken out of the city-wide straitjacket of right angles and smooth surfaces – as if Gaudi had taken up skyscraper design, or a spinning ballerina had morphed into a building...

....As it happens, Gang is immensely fond of birds. In the design of the Aqua Tower, she has paid careful attention to the way birds see – or don't see – sheer glass walls, helping them to avoid fatal collisions. (A building with a complex facade is much safer for them, as are irregular window bars; birds pick up on the irregularity.) In her office, Gang has a number of bird's nests lined up on a window sill; she says she admires their spare, essential beauty.]
http://www.guardian.co.uk/artanddesign/2009/oct/20/aqua-tower-jeanne-gang

http://en.wikipedia.org/wiki/Aqua_(skyscraper)