America’s National Park Service (NPS) celebrates its 100th birthday on Aug. 25. From Aug. 25 to Aug. 28, parks across the country will be offering free entry, along with everything from solar-powered vehicle races to classical music performances to outdoor naturalization ceremonies. Famously called “the best idea we ever had” by writer Wallace Stegner, the NPS was founded in 1916 by an act of Congress in order to conserve and protect America’s natural wonders.