Lights blinked off in Chicago and around the world tonight to mark Earth Hour, an international effort to raise awareness about climate change.
From 8:30 p.m. to 9:30 p.m. local time around the globe lights were turned off in landmarks, businesses and homes, saving energy as a symbol to support efficiency and ecology.
Wrigley Field marquee hosted a ceremony by turning off excess lights, and other landmarks such as the Wrigley Building, NBC Tower joined suit along with City Hall, the Cultural Center, Public Safety Headquarters, and additional city facilities.
Hundreds of other buildings, institutions and landmarks throughout the Chicago area -- including Chase Tower, the James R. Thompson Center and Willis Tower -- planned to take part.
Earth Hour is observed on the last Saturday of March when everyone is asked to turn off all non-essential lights for an hour.
The annual event has grown from a one-city initiative to a global movement with more than 5,200 cities becoming involved since 2007, officials said in a news release.
Earth Hour, organized by the World Wildlife Fund, has reached about 1.8 billion people in 135 countries globally, officials said.