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The Sears Tower, second from left, leads the way by dimming the tower lights during the World Wildlife Fund's Earth Hour event  in Chicago, Saturday, March 29, 2008.  The environmental group WWF urged governments, businesses and households to turn back to candle power for at least 60 minutes Saturday starting at 8 p.m. wherever they were. Several U.S. cities including Chicago and Atlanta participated and symbolic darkouts or dimmings of monuments.(AP Photo/Charles Rex Arbogast)