The Forbidden City, a major symbol of Chinese culture, will join many other landmarks worldwide in turning off its lights for one hour on Saturday to raise awareness of climate change.

It will be the first time for the 600-year-old imperial palace and UNESCO World Heritage Site to participate in Earth Hour, which has been occurring on the last Saturday of March since 2007.

Two other iconic structures in the capital, the Water Cube and Bird's Nest, will join the palace and have their lighting turned off from 8:30 pm to 9:30 pm, said Earth Hour organizer World Wildlife Fund (WWF) on its website.

"Last year, we turned off the Bird's Nest in the Olympic park. This year, the Forbidden City. We are extremely impressed with the level of support the city of Beijing has shown for Earth Hour," said Dermot O'Gorman, WWF China's country representative.

More Chinese cities and people are expected to mark the event by turning off lights.

WWF China's communications consultant Ye Hongna said that by Friday afternoon, at least 32 cities in China, including Shanghai, Xi'an, Chengdu and Hong Kong, had vowed to join in the activity.

More than 1.5 million Chinese people have also pledged on WWF China's website as well as other major Chinese portals to turn off their lights at home on Saturday, Ye said.

Shanghai will join the event for the second year.

The municipal government has promised to turn off lights that delineate the metropolitan skylines, including the lights in the Lujiazui area, where two of China's tallest buildings stand.

Netizens have similarly planned various ways to spend the hour without lighting. Many said they would spend a romantic hour with their loved ones by wandering around under starlight, while others said they would catch up with friends in the dark.

"Earth Hour will provide a good opportunity to watch the stars, which are always outshined by terrestrial light pollution," said Wang Zhiping, 33, an engineer from Shanghai.

"More importantly, every one of us should save energy as much as we can in daily life, not just in one day," he said.

At least 3,700 cities and towns in 125 countries and regions across every continent have confirmed to go dark for Earth Hour 2010 by Friday, according to WWF China. It is expected to be the world's greatest display of action on climate change, it said.

China joined the event starting last year, when about 20 cities participated in the event for the first time.