Cities across the world switched off their lights to mark this year's 'Earth Hour' movement on Saturday.
In Europe, London's iconic Big Ben and Westminster Palace dimmer their lights as well as, Milan's Sforza Castle and Madrid's Almudena Cathedral.
The event is aimed at raising awareness of conservation. Earth Hour was launched in 2007 as a solo event in Sydney, Australia, with more than two million people involved.
Organisers said they wanted to demonstrate what people can do to reduce their carbon footprint and save energy, thereby drawing attention to the problems of climate change.
Times Square before and during Earth Hour in New York:
Big Ben and the Houses of Parliament which went dark for an hour tonight as the UK took part in Earth Hour.
The UNESCO World Heritage Cologne Cathedral and the Hohenzollern railway bridge along the river Rhine:
The Acropolis before and during Earth Hour in Athens:
The Kremlin before and during Earth Hour in Moscow:
India Gate before and during Earth Hour in New Delhi:
The National Stadium, also known as the "Bird's Nest", reflected in a lake before and during Earth Hour at the Olympic Park in Beijing: