It's lights out for Chicago on March 29

Chicago Mayor Richard M. Daley says it will be lights out for many of the city's public buildings on March 29.

Daley said Friday that on that date Chicago will join more than 20 other cities around the world for an hour of voluntary energy conservation. He called it "a symbolic gesture to remind us that we all share the responsibility of global warming."

Exterior lights on public buildings will go dark from 8 to 9 p.m. as part of Earth Hour 2008. Switches will also be flipped off on major privately owned Chicago buildings, including such landmarks as the Merchandise Mart, Sears Tower and the John Hancock Center.