Plant Your Roof

It's a wonder that this concept attributed to the Hanging Gardens of Babylon, one of Seven Wonders of the World, didn't catch on sooner in the modern world. Legend has it that the roofs, balconies, and terraces of the royal palace of Babylon were turned into gardens by the king's order to cheer up one of his wives. Roof gardens help absorb heat, reduce the carbon dioxide impact by taking up CO2 and giving off oxygen, absorb storm water, and reduce summer air conditioning usage. Ultimately, the technique could lessen the "heat island" effect that occurs in urban centers. Butterflies and songbirds could also start frequenting urban garden roofs, and like the king's wife, could even cheer up the inhabitants of the building. Here, a green roof is tested at Chicago's City Hall.