Originated in Sydney in 2007, Earth Hour is a global event held annually on the last Saturday of March to raise awareness of the need to protect the environment. During the Earth Hour, from 8:30 p.m. to 9:30 p.m., cities turn off lights on landmarks, streets and business buildings. Millions of concerned citizens also turn off all non-essential lights in their homes. Following Sydney's lead, many other cities around the world have adopted the event.