Aqua Tower

Source: Steve Hall / Hedrich Blessing

Thanks to the Aqua Tower in downtown Chicago, it's now possible to get vertigo by looking up.

Completed in 2009 at a cost of over $300 million, Aqua rises 82 stories above Chicago's Lakeshore East development. The facade is a multi-dimensional mix of glass and concrete slabs separating the floors with nautically-inspired undulations, giving the tower an appearance of being draped in rippling fabric.

Source: Dan Gregory / Eye on Design

Aqua's design is the brainchild of Jeanne Gang of Studio Gang Architects, and is the highest building in the world designed by a woman. Incorporating design cues from the wind-shaped limestone cliffs along the Great Lakes, the residential tower also won the Emporis Skyscraper Award, earning best of the year in 2009. Not bad, considering this was Gang's first skyscraper project.

Source: Dan Gregory / Eye on Design

Studio Gang designed the Aqua with sustainability in mind, incorporating features like advanced water collection systems, terraces shaped and placed for maximum shading, and a massive green roof up top. Wildlife was also taken into consideration: the design of high-contrast etched glass and wavy concrete makes the tower more visible to our feathered friends, earning PETA's Proggy Award (recognizing progress in animal-friendly design) in 2009 for its bird-friendly features.