See how the world participated in Earth Hour. On March 27, over a billion people turned off their lights and electrical appliances for one hour. Earth hour is a global sustainability movement organized by WWF to raise awareness towards the need to take action on climate change. Here are 24 before and during photos of Earth Hour.

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Rollover to see the photos with the lights off.

The Angel of Independence was one of the points were the Earth Hour ceremony took place in 2010. | © WWF / Luis Cortés

The unlit skyline of Auckland, New Zealand, cbd during earth hour 2010. | © WWF / Chris Gorman

Lights go out at China's National Stadium - The Bird's Nest - for Earth Hour 2009 in Beijing. | © WWF / Janek Zdzarski

Jakarta Landscape | © WWF-Indonesia / Fandi Hastomi

The Forbidden City is shrouded in darkness with its lights are turned off as WWF China holds a Earth Hour event at its north gate in Beijing, China. 27 March 2010. Earth Hour is a global call to action to every individual, every business and every community throughout the world. Hundreds of millions of people around the world will come together to call for action on climate change by turning off their lights for one hour. | © WWF/Simon Lim

Sydney Harbour with the Sydney Opera House and the Sydney Harbour Bridge after lights out in support of Earth Hour 2010. | © Sewell / WWF 2010 NOT FOR ARCHIVE OR RESALE

Strip from the Rio, Las Vegas, NV, USA with lights out. | © WWF / Bill Hughes

The Parliament Palace, Bucharest, before turning off the lights. The switch off was followed by a mass event, Romania. Earth Hour 2010. | © WWF/Stefan Angelescu

Bank of China, Cheung Kong Centre, HSBC Building, Standard Chartered Building, Legco Building, Hong Kong after lights out, Earth Hour 2010 | © WWF-Hong Kong

Sabancı Twin Towers and Istanbul, Turkey, Earth Hour 2010 | Credit: © Teoman Aydın

The Egypt skyline showing The Sphinx and The Pyramids are seen after the lights are switched off for Earth Hour 2010 in Cairo, Egypt. | © Jason Larkin