SAN FRANCISCO - JUNE 7 : Workers work on the living roof of the new California Academy of Sciences building in Golden Gate Park on June 7, 2007 in San Francisco, California. The living roof, a 2.5 acre expanse will feature 7 hills blanketed with over 1.7 million individual plants of 9 different species native to Northern California that thrive in the Golden Gate Park environment. The museums roof will not only help reduce the energy needed for the building by 30-35% but will also create a new habitat for wildlife such as hummingbirds, bumble bees and endangered species such the Hairstreak and San Bruno butterflies. The new museum, which was designed by architect Renzo Piano, will open in 2008.