Washington D.C. leads the nation in green roofs! In terms of square footage, the nations capital also is the capital of urban architectural vegetation. Green roofs are much more than simply plants on a roof, or on a wall. They are the future of architecture and design, as they often integrate cutting edge water, energy, and A/C utilities. Green roofs also have environmental advantages such as carbon recapture, by which plants clean the air, and overall reduced heat emitting from buildings which helps reduce the Urban Heat Island effect. Read more
here.