Antarctica to Pyramids -- lights dim for Earth Hour CHICAGO - From an Antarctic research base and the Great Pyramids of Egypt to the Empire State Building in New York and the Sears Tower in Chicago, illuminated patches of the globe went dark Saturday for Earth Hour, a campaign to highlight the threat of climate change. Sydney first major city to mark Earth Hour 2009 SYDNEY - The floodlit cream shells of the famed Opera House dimmed Saturday as Sydney became the world's first major city to plunge itself into darkness for the second worldwide Earth Hour, a global campaign to highlight the threat of climate change.