The lights were switched off around the world at 8:30 p.m. on Saturday evening, to mark the 10th annual Earth Hour, and to draw attention to climate change.
The initiative began in Australia in 2007 as a grass roots gesture by the World Wildlife Fund (WWF) Australia against man-made carbon dioxide emissions linked to a warming planet.
In 2017, it involved the switching off of electric lights for an hour in 7,000 cities across 172 countries, at 8:30 p.m. local time, with the aim of highlighting the need to act on climate change, and saving a few megawatts of power in the process.
Among the famous buildings and structures taking part in Australia are Sydney's Opera House, the Harbour Bridge, Luna Park, Town Hall, and Sydney Tower Eye.
Internationally the list includes some of the world's best known sky-scrapers and historic buildings including the world's tallest building, the Burj Khalifa in Dubai, London's Big Ben and Houses of Parliament, the Colosseum in Rome, Istanbul's Blue Mosque, the Eiffel Tower, Moscow's Kremlin and Red Square and the Pyramids of Egypt.
While the organisers of Earth Hour said they do not audit results of the energy saving initiative, the group has commissioned research indicating up to one in four Australians gets involved.
WWF says Earth Hour can take credit for various environmental initiatives, like the 2013 declaration of a 3.4 million hectare marine park in the waters off Argentina, the planting of a forest in Uganda and a ban on soft plastics in the Galapagos Island.
(With agency inputs)
1. This is how Austria's Belvedere palace is usually lit up
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Belvedere palace and its reflection in a pond before the lights were switched off for Earth Hour in Vienna, Austria.
Image courtesy: Reuters
2. Lights off: Austria's Belvedere palace in darkness for Earth Hour
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A long exposure shows Belvedere palace and its reflection in a pond after the lights were switched off for Earth Hour in Vienna, Austria, March 25, 2017.
Image courtesy: Reuters
3. Russia's Red Square in the dark
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A view shows the St. Basil's Cathedral (L) and the Kremlin wall, after the lights were switched off for Earth Hour in Red Square in central Moscow.
Image courtesy: Reuters
4. Before: The hill of the Acropolis in Greece
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The hill of the Acropolis is pictured before Earth Hour in Athens, Greece, March 25, 2017
Image courtesy: Reuters
5. After: The hill of the Acropolis in Greece plunges into darkness
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The hill of the Acropolis is pictured during Earth Hour in Athens, Greece
Image courtesy: Reuters
6. Before: Another image from Russia
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A view shows the illuminated Kremlin after Earth Hour in central Moscow, Russia
Image courtesy: Reuters
7. Russia switches off for Earth Hour
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A view shows the Kremlin during Earth Hour in central Moscow, Russia
Image courtesy: Reuters
8. Russia
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A view shows the illuminated Kremlin after Earth Hour in central Moscow
Image courtesy: Reuters
9. Russia
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A view shows Kremlin during Earth Hour in central Moscow
Image courtesy: Reuters
10. Before: Mexico's 'Angel de la Independencia' lit up
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People stand by "Angel de la Independencia" monument before the lights were turned off for Earth Hour in Mexico City, Mexico, March 25, 2017
Image courtesy: Reuters
11. After: Lights off at the 'Angel de la Independencia' in Mexico
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People stand by "Angel de la Independencia" monument after the lights were turned off for Earth Hour in Mexico City, Mexico
Image courtesy: Reuters
12. Pakistan's Frere Hall building before Earth Hour
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The Frere Hall building is seen illuminated minutes before Earth Hour in Karachi, Pakistan March 2
Image courtesy: Reuters
13. Pakistan's Frere Hall building during Earth Hour
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The Frere Hall building is seen during Earth Hour in Karachi, Pakistan
Image courtesy: Reuters
14. Before: Sydney's Opera House lit up
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The Sydney Opera House seen before the tenth anniversary of Earth Hour in Sydney, Australia
Image courtesy: Reuters
15. After: Sydney's Opera House switches off in support of Earth Hour
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The Sydney Opera House seen during the tenth anniversary of Earth Hour in Sydney, Australia
Image courtesy: Reuters
16. Phillipines
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This image shows the globe in front of a mall before the Earth Hour environmental campaign in Manila on March 25, 2017.
Image courtesy: AFP
17. Phillipines
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This image shows the globe in front of a mall during the Earth Hour environmental campaign in Manila, Phillipines
Image courtesy: AFP
18. Before: Mumbai's CST is lit up
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Traffic moves in front of the Chhatrapati Shivaji Terminus (CST), before the lights were turned off for Earth Hour in Mumbai, India, March 25, 2017.
Image courtesy: Reuters
19. After: CST switches off for Earth Hour in Mumbai
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Chhatrapati Shivaji Terminus (CST), after the lights were turned off for Earth Hour in Mumbai
Image courtesy: Reuters
20. Brazil's Christ the Redeemer statue in all its lit glory
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The statue of Christ the Redeemer is seen before being plunged into darkness for the Earth Hour environmental campaign on top of Corcovado hill in Rio de Janeiro, Brazil, on March 25, 2017.
Image courtesy: AFP
21. Brazil's Christ the Redeemer statue plunges into darkness
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The statue of Christ the Redeemer is seen after being plunged into darkness for the Earth Hour environmental campaign on top of Corcovado hill in Rio de Janeiro, Brazil
Image courtesy: AFP
22. Before: Akshardhan Temple in New Delhi
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The temple, Akshardham illuminated before Earth Hour.
Image courtesy: DNA
23. After: Akshardhan Temple in New Delhi switches off
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The temple, Akshardham turned off its lights for Earth Hour.
Image courtesy: DNA
24. France's Eiffel Tower lit up
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The Eiffel Tower is pictured before Earth Hour in Paris, France, March 25, 2017 at which lights are switched off around the world at 8:30 p.m. on Saturday evening to mark the 10th annual Earth Hour and to draw attention to climate change.
Image courtesy: Reuters
25. France's Eiffel Tower plunges into darkness for Earth Hour
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The Eiffel Tower is pictured during Earth Hour in Paris, France.
Image courtesy: Reuters
