The Forth Bridge is usually illuminated by spotlights at night
Dozens of Scotland's landmark buildings were plunged into darkness as part of a global campaign highlighting climate change.
Edinburgh Castle, the Forth Bridge, the Falkirk Wheel and the Wallace Monument were be among those taking part in WWF's Earth Hour on Saturday evening.
The environmental group had urged millions of people around the world to switch off their lights at 2030 GMT.
WWF called for a "show of support for decisive action on climate change".
Earth Hour started in 2007 in Sydney, Australia, when 2.2 million homes and businesses turned their lights off for one hour.
WWF said about 2,800 cities and towns in more than 80 countries had supported the event.
In Scotland, 19 local authorities, 200 schools and more than 100 businesses and organisations agreed to take part.
Landmarks such as Eilean Donan Castle, Inverness Castle, Stirling Castle and Glasgow's Clyde Arc (Squinty bridge) and Armadillo were in darkness as part of the campaign.
The Scottish Parliament also took part alongside global sites such as the pyramids of Giza, Sydney Opera House, the Eiffel Tower, the Golden Gate Bridge and the Empire State Building.
WWF hopes this public support will convince governments across the world to agree to take effective action to tackle climate change, when they meet at the UN Climate Summit in Copenhagen in December.
Speaking ahead of the event, Dr Richard Dixon, director of WWF Scotland, said: "WWF's Earth Hour promises to be the biggest show of support ever for action on climate change.
"By signing up to switch their lights off, millions of people will be showing world leaders that they care about tackling climate change.
"This is a simple way for people to show their support for strong action on climate change."