Earth Hour 2015 will happen at 8:30 p.m. Saturday, when landmarks, hotels, universities, buildings and individuals shut off their lights to raise awareness of climate change. It's an hour -- based on local time wherever you are -- meant to be a call to action too.
The World Wildlife Fund organizes the annual event, which started in 2007 in Sydney, Australia. The organization reports that 7,000 cities, 1,200 landmarks and 172 countries and territories will go dark this year.
The Eiffel Tower in Paris, the Brandenburg Gate in Berlin and Times Square in New York City are among the landmarks that plan to participate. You can stay home and turn out the lights or go to these events and places.
Las Vegas: Casinos and hotels on the Strip will power down their exterior lighting and marquees, leaving one of the world's most famous roadways in darkness.
Los Angeles: The blue glow of Staples Center, Pacific Park's Ferris wheel at the Santa Monica Pier and the colorful pylons at Los Angeles International Airport will go dark.
San Francisco: Ghirardelli Square is dousing the lights and throwing a #GoDark Earth Hour Party from 6 to 9:30 p.m. It's a dark chocolate (get it?) tasting party too. The Golden Gate Bridge and Transamerica Pyramid building will cut the lights too.
Ritz-Carlton and Hilton hotels: Some hotels around the world will switch off non-essential lights at all properties and organize events too. The Ritz-Carlton says in a statement that its hotel in Dubai's International Financial Center will host "Stories by Candlelight" for kids while guests at the Istanbul Ritz-Carlton will be treated to a traditional Turkish shadow play in the lobby.
Hilton hotels are participating too. The Conrad Macao, Cotai Central will turn off external lights, dim indoor lights in restaurants and lounges, and create a 280-candle display of the Earth Hour logo in the lobby.
UNESCO sites: Thirty UNESCO World Heritage Sites will go dark, including the Acropolis in Athens, Edinburgh Castle in Scotland and the Cologne Cathedral in Germany.
Info: Find an event or location near you at Earth Hour 2015.