(Agencies)
Updated: 2008-03-31 06:32

LONDON/SAN FRANCISCO -- From the Sydney Opera House to San Francisco's Golden Gate Bridge, iconic structures went dark as people switched off lights in their homes and skylines dimmed around the world on Saturday to show concern with global warming.

Up to 30 million people were expected to have turned off their lights for 60 minutes by the time "Earth Hour" - which started in Suva in Fiji and Christchurch in New Zealand - completed its cycle westward.

Diners eat by candlelight outdoors at a restaurant participating in the Earth Hour event in Manila March 29, 2008. People switched off lights across the world on Saturday, dimming buildings, hotels, restaurants and bars to show concern at global warming. [Agencies]

More than 380 towns and cities and 3,500 businesses in 35 countries signed up for the campaign that is in its second year after it began in 2007 in Sydney, Australia's largest city.

"Earth Hour shows that everyday people are prepared to pull together to find a solution to climate change. It can be done," said James Leape of WWF International, which was running the campaign.

Lights at Sydney's Opera House and Harbor Bridge were dimmed as Australians held candle-lit beach parties, played poker by candlelight and floated candles down rivers.

In Bangkok, some of the city's business districts, shopping malls and billboards went dark, although street lights stayed on. One major hotel invited guests to dine by candle light and reported brisk business.

In Copenhagen, the Tivoli Gardens and the Royal Palace and the opera darkened for an hour, along with many street lights.

"In the central square a lot of people were standing looking at the stars," said Ida Thuesen, spokeswoman for WWF Denmark. "It's not often you can see the stars in a city."

In a tip of its virtual hat to the event, the background of Google's home page turned to black from white on more than a dozen country sites including Google.com. Floodlights went out at landmarks in Budapest, including its castle, cathedral and parliament.

In Britain, 26 town and city councils signed up to switch off nonessential lights as did several historic buildings, including Prince Charles' private residence Highgrove House, London City Hall, Winchester Cathedral and the Government Communication Headquarters radio monitoring station. The south coast town of Brighton turned off the lights on its pier.

The movement crossed the Atlantic to the United States and Canada, where the 553-metre CN Tower in Toronto and the surrounding skyline were plunged into temporary darkness.