( CNN ) -- Looking for something free to do this weekend ? Check out a national park . Entrance fees will be waived at all U.S. national park sites this Saturday and Sunday , April 19-20 , to kick off National Park Week , which runs through April 27 . Visitors still have to pay the usual fees at campgrounds and concession stands . With more than 400 National Park Service sites covering 84 million acres in the United States , there are plenty of spots to explore . And if you think national parks are just places where you can take a hike or be one with nature , think again . The Statue of Liberty is a national park . So is Gettysburg National Military Park . Parks and scenic trails like Yellowstone National Park in Montana are not the only areas that make up the National Park Service . Monuments , battlefields and historic sites are also given this distinction . `` National parks are closer than many people think ; every state has at least one , '' said Kathy Kupper , a spokeswoman for the National Park Service . `` These range from big natural parks to smaller historical sites . '' In addition to free admission this weekend , many parks are offering special events throughout the week . You can participate in the `` waterfall challenge '' at California 's Whiskeytown National Recreation Area , commemorate the opening battle of the American Revolutionary War at Minute Man National Historic Park in Massachusetts or experience how Civil War soldiers lived in a living history encampment weekend at Appomattox Court House National Historic Park in Virginia . Many of the parks will have special activities for kids on National Junior Ranger Day on April 26 . In 2013 , national parks across the country saw 273.6 million visitors , with an average of 784,000 visitors per day during the month of April when National Park Week is always observed . `` National Park Week definitely raises awareness of national parks as great places to visit , '' Kupper said . `` April is a good time , as the weather gets better , to remind people of all the great opportunities to get up and get out in a park . '' What do you consider the world 's best national park ? Share your photos with CNN iReport .
April 19-27 is National Park Week in the U.S. All parks are free to enter Saturday and Sunday , April 19-20 . Campground and concession fees still apply . What 's the best national park in the world ? Comment: