Walking is one of those activities that's not only healthy for you, but good for the planet too. The Wind Tunnel Footbridge is part modern sculpture, part green technology, and part weird. Surrounding the bridge are five bladed wheels that spin like windmills when the breeze picks up. Each wheel spins in an opposite direction and at varying speeds to make optimal use of wind direction. From a distance it looks like a modern work of art, but I can't imagine walking through the thing as I'm sure I would experience the same motion sickness I get when walking through a fun-house tunnel. Best of all, this concept bridge is able to harness the wind that propels it to produce and store energy.

Designer Michael Jantzen thinks these could be constructed at public attractions like museums and parks, but I would really like to see these replace skywalks across highways. Regardless, this bridge seems to be a heck of a lot safer than walking on a 4-inch piece of glass suspended over the Grand Canyon. — Stephen Schleicher

Michael Jantzen, via Treehugger