The municipal buildings in Minneapolis will go dark for one hour on March 29 in observance of "Earth Hour." Many privately owned buildings downtown will join them, including theaters, the Wells Fargo Center and the IDS Center. Lights required for "life, safety or operations" will stay on, according to the city announcement.
Sydney, Australia started the trend last year and now cities across North America, Asia and Europe are joining in. The point is to raise awareness of global warming.
I'll be interested to learn how much energy is saved in that short period of time and whether the buildings participating will take more steps towards energy efficiency themselves.