With the demand for fresh local produce on a upward spiral, so is the demand for growing space. And that, in turn, inspires innovation and invention. A good example of this forward-thinking approach is the Urban Garden at O'Hare International Airport in Chicago. On the mezzanine level of one of the busiest airports in the world, travelers will find a 928-square-foot organic oasis that features nearly 50 kinds of vegetables and herbs. The technique that makes the indoor garden possible is aeroponics, a method of cultivating plants without soil but with a nutrient-rich solution that is misted onto their roots.