STORY: Earth Hour, a worldwide movement organized by the WWF, encourages individuals, communities, and businesses to turn off non-essential lights for an hour on the last Saturday of March, in a symbolic commitment to tackle climate change.

It was first launched in Sydney in 2007 and has since become a global movement, taking place in 188 countries and territories.

Italy's ancient Roman Colosseum and Australia's iconic Opera House and Harbour bridges plunged into darkness as part of the campaign, as well as the tourist attractions in other global cities.

Millions of people in over 7,000 cities in 190 countries were expected to turn off their lights to show solidarity and commitment to saving the planet.