Famous buildings and monuments around the world will be plunged into darkness on March 29 to honour the global environmental initiative Earth Hour. In North America, the Golden Gate Bridge in San Francisco, the Empire State Building in New York and the Space Needle in Seattle are just some of the legendary sites which will be dimming their lights for the event. Earth Hour USA has launched a social media campaign to encourage buildings such as Navy Pier in Chicago and the Alamo Shrine in Texas to take part. On the Canadian border, even Niagara Falls will see its power...