Fireworks, barbecues, and parades are perhaps the most common Fourth of July celebrations. While perhaps more solemn, visiting some of the numerous national monuments and memorials is another perfect way to observe Independence Day. Writer and historian Wallace Stegner called national parks, “Absolutely American, absolutely democratic.”

The National Park Service, established nearly 100 years ago, tracks the number of visits to each of its nationally recognized sites. Of the 368 national parks for which data is available, 24/7 Wall St. specifically reviewed annual visits to the 79 national monuments and memorials. The Lincoln Memorial in Washington D.C. is the most popular, with 6.8 million visits a year. Only 12 of the 79 locations receive more than 1 million visitors in a given year. Walnut Canyon in Arizona rounds out the list in 50th place, with 129,914 visitors annually.

The Lincoln Memorial, Statue of Liberty, Washington Monument, and other such structures are of course man-made. However, the federal government also designates natural features to commemorate historical events, individuals, or — as is true for national parks — to preserve and protect landmarks, historic, and prehistoric structures. Of the 50 most visited national monuments, close to half are features of the natural landscape.

Click here to see the 50 most popular monuments.

For example, the John Day Fossil Beds National Memorial in Oregon and the Dinosaur National Memorial in Colorado protect fossil records. Similarly, the Organ Pipe Cactus National Memorial was established to preserve the only known place in the world where the organ pipe cactus grows wild.

Congress has the power to proclaim monuments and memorials, as does the president. The Antiquities Act of 1906 authorized presidents to create national monuments on federal lands. The act was intended to allow for swift protection of lands and objects of great interest. However, presidential establishments of monuments and memorials have not always been undisputed. Franklin Roosevelt’s Jackson Hole National Monument in Wyoming, Jimmy Carter’s designation of 56 million acres in Alaska, and Bill Clinton’s proclamations of 19 monuments were all contentious.

To identify the most visited U.S. monuments and memorials, 24/7 Wall St. calculated average annual visits to U.S. monuments and memorials from 2011 through 2015 from the National Park Service, a bureau of the U.S. Department of the Interior.

These are the most visited U.S. monuments and memorials.