WWF's Earth Hour is the world’s largest display of hope for a bright future. From London to Sydney, New York and Singapore, people all across the world will be switching out their lights for one hour to show they care about tackling climate change and protecting the natural world.
In Scotland, thousands of people switched off at the same time as iconic landmarks such as Edinburgh Castle, the Scottish Parliament, Falkirk Wheel, Kelvingrove Museum and the Wallace Monument.
Earth Hour 2011 in Scotland will be the biggest and best yet. There is more than switching off the lights - check out all the ways you can get involved.