When Chicago's Sears Tower was completed in 1973 the 110-story building was the tallest in the world, and it offered a bold example of the human potential to build towards the clouds. Now, although the tower lost the title of tallest building to other skyscrapers in the 1990s, the tower hopes to dazzle the world anew with a fresh vision of urban architecture: The building will soon receive a $350 million environmental retrofit, with wind turbines, solar panels, and gardens all added to the building's staggered rooftops.