Landmark buildings throughout the globe plunged into darkness on March 25, an effort to mark Earth Hour and draw attention to climate change.
The Kremlin and Bolshoi Theater in Moscow, the Empire State Building and UN headquarters in New York, the Eiffel Tower in Paris, and Acropolis in Athens were among iconic buildings and monuments in at least 170 countries to turn lights out for 60 minutes.
The event was originated in Sydney, where the city’s famed Opera House also dimmed its lights to mark the occasion.
The World Wild Fund for Nature (WWF) conservation group organized the event.
"We started Earth Hour in 2007 to show leaders that climate change was an issue people cared about," coordinator Siddarth Das said.
Scientists said the Earth last year registered the hottest temperatures in modern times for the third year in a row.