We can learn a lot from ancient civilizations, but urban planners are learning even more by studying the ruins of the Inca kingdom. A new exhibit at the Smithsonian in Washington DC shows how the Incas helped move water away from roads (and thereby preserving them) and reducing erosion from runoff. As the United States grapples with how to update our aging infrastructure, maybe we should look to ancient civilizations for inspiration and ideas.

First, there were green roofs - roofs that included plants as a part of design to reduce urban runoff and the heat island effect. The ideas around green roofs have advanced to now include "food roofs" where urban agriculture can play double duty to also include greenhouses, beehives and community spaces. St. Louis is in the spotlight with urban agriculture with a new 10,000 sf rooftop farm unvailed last month. In addition to vegetable production, this unique food roof is he