<p>Egypt's famous sphinx sits bathed in floodlights near the Giza pyramids before Earth Hour 2009. More than 4,000 cities in 87 countries and several iconic landmarks went dark last year during the third annual Earth Hour. The initiative, run by the conservation nonprofit WWF, was designed to spark global interest in combating climate change. For 2010, Earth Hour will take place on March 27 at 8:30 p.m. local time.</p>

Pyramids Before Earth Hour 2009

Egypt's famous sphinx sits bathed in floodlights near the Giza pyramids before Earth Hour 2009. More than 4,000 cities in 87 countries and several iconic landmarks went dark last year during the third annual Earth Hour. The initiative, run by the conservation nonprofit WWF, was designed to spark global interest in combating climate change. For 2010, Earth Hour will take place on March 27 at 8:30 p.m. local time.

Photograph courtesy World Wildlife Fund

Earth Hour Pictures: Lights On, Lights Off

As hundreds of cities prepare to dim their skylines for Earth Hour 2010, see before-and-after shots of the empowering event in years past.

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