(WTVM/CNN) - Lights out! Millions of people across the world are expected to turn off the lights for one hour Saturday, March 29.
The Worldwide Fund for Nature encourages people, cities, businesses and landmarks to switch of the lights at 8:30 p.m. local time.
The annual Earth Hour started in 2007, and is aimed at showing support for environmental causes. Famous landmarks expected to turn off the lights include New York City's Empire State Building, Berlin's Bradenburg Gate, and the Eiffel Tower in Paris.
Others include the Houses of Parliament and Buckingham Palace in England, and many others.
USA Today estimates more than a billion people take part in Earth Hour.