Hilton Hotels in Prague, plan to mark Earth Hour 2011 from 8:30 p.m. – 9:30 p.m. local time on Saturday, March 26, 2011 as people and organizations around the world turn off their lights in support of action on global climate change. Hilton Hotels in Prague and many of the 3,500 hotels that are part of the Hilton Worldwide portfolio of brands are expected to take part in the event that will mobilize more than one billion people worldwide.