A few photos from around the world of cities that participated in Earth Hour 2009.
Nearly 4,000 cities and towns in 88 countries took part in an effort to call attention to climate change. The event, sponsored by the World Wildlife Fund, called on cities to dim nonessential lights from 8:30 to 9:30 p.m.


Earth Hour Sydney
This combination photograph shows the Sydney Harbor Bridge and Sydney Opera House illuminated prior to Earth Hour (top) and turned off during Earth Hour (bottom) on March 29, 2008. (Photo by Ian Waldie/Getty Images)


Earth Hour London
The Houses of Parliament in central London, after the lights are turned off to mark Earth Hour. (Leon Neal/AFP/Getty Images)


Earth Hour Greece
The Ancient Parthenon Temple atop the Acropolis hill is pictured during its lights out as Greece participates in Earth Hour in Athens. (ARIS MESSINIS/AFP/Getty Images)


Earth Hour Manila
This picture combo shows a view of the Manila skyline from the bay before and during lights out as the Philippines participate in Earth Hour on March 28, 2009. (Photo by Jes Aznar/AFP/Getty Images)


Taipei Earth Hour
This picture shows the Taipei 101 building with its lights shut off to mark Earth Hour in Taipei on March 28, 2009. (Photo by Sam Yeh/AFP/Getty Images)


Hong Kong Earth Hour
This combo shows (L to R) the Bank of China building, the Cheung Kong Centre, the HSBC Building and the Standard Chartered Bank building and the colonial Legislative Council building (bottom L) just before Earth Hour (pictured top) and then during (pictured bottom) as Hong Kong turns out its lights on March 28, 2009. (Photo by Mike Clarke/AFP/Getty Images)



Chicago Earth Hour
Spectators gather along the shore of Chicago's Lake Michigan to watch the lights go off and on in downtown buildings for Earth Hour held on March 29, 2008. (Photo by Scott Olson/Getty Images)


Malaysia Earth Hour
These two combo photos show Malaysia's landmark Petronas Twin Towers being turned off the lights to mark Earth Hour in downtown Kuala Lumpur, Malaysia, Saturday, March 28, 2009. (AP Photo/Lai Seng Sin)


Egypt Earth Hour
A combination photo of a night view of the site of the ancient Giza Pyramids before and after switching off the lights for the Earth Hour, in Cairo, Egypt. (AP Photo/Nasser Nouri)


Toronto Earth Hour
The skyline of Toronto's downtown is dimmed as many of the lights are turned off for Earth Hour on  Saturday, March 28, 2009. (AP Photo/The Canadian Press, Darren Calabrese)


Las Vegas Earth Hour
Lights on the Las Vegas Strip are viewed looking northbound from the Mandalay Bay Resort just before “Earth Hour” in Las Vegas, then after many of the lights went off as the event began at 8:30 Saturday night. (Las Vegas Sun, Steve Marcus)