(CNN) — From the giant sequoias of Yosemite to the geysers of Yellowstone, the United States' national parks were made for you and me.
And for Saturday and Sunday, they're also free.
Though most of the National Park Service's 407 sites are free year-round, the 128 parks that charge a fee -- like Yellowstone and Yosemite -- will be free those two days.
Check out night-time astronomy parties, daytime Revolutionary War programs, Earth Day parties and family-friendly Junior Ranger activities at national park sites across the country.
Not sure how to start? Go to FindYourPark.com to learn more about park sites near you. Go to www.nationalparkweek.org for more ideas on how to explore. Then the park service wants people to share their stories using the hashtag #FindYourPark and at FindYourPark.com.