Look at this thing. It’s a wall of greenery planted onto the side of an otherwise nondescript building, a 78-foot-high vertical garden, a work of art. It stand outside the CaixaForum gallery not far from the Prado, and even though Madrid is a city where one gets used to surprises, this “living painting” of 15.000 plants from some 250 species by French artist Patric Blanc comes as a surprise. Blanc believes that “plants don’t need earth: only water, minerals, light and carbon dioxide,” and he’s been putting his belief into practice, building these vertical gardens since 1988 in such places as Paris, Osaka, New York, Bangkok, New Delhi and Genoa. He hopes gardens such as these will be created in train stations, parking lots, the metro, “those difficult spaces where you don’t expect to see greenery.” Surprise!