Iconic skyscrapers find new luster by going green (AP)

FILE - In this Oct. 29, 2008 file photo, the Empire State Building, center, is illuminated by sunlight against a cloud-darkened sky in New York. When owners of the Empire State Building decided to give it a $120 million environmental makeover, in 2009, they were only partly interested in saving energy.(AP Photo/Kathy Willens, File)AP - When owners of the Empire State Building decided to blanket its towering facade this year with thousands of insulating windows, they were only partly interested in saving energy. They also needed tenants.