At this Minnesota state park you can easily wade across the source of the mighty Mississippi.

The watery grave of an impractical idea.

In the middle of a New England forest sit the crumbling ruins of World War II-era ammunition storage bunkers.

Around half a million years ago, these magnificent columnar basalt cliffs were formed from cooling lava.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The first declared National Monument in the United States.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

A beautiful geyser under environmental threat.

Comprised of Spanish war cannons, this sculpture once graced the bow of a WWI warship.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

Remnants of a wall built to separate Black residents of Hall's Hill from a newly built subdivision are a grim reminder of segregation in 20th-century Virginia.

The fifth-longest natural arch in the world, and the longest outside China.

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

A tunnel with windows, so you don't miss out on the impressive views.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Three hundred years of preserved Spanish colonial history in San Antonio.

A series of life-sized statues of each governor of the state of South Dakota.

This vintage train once gave new meaning to “swimming upstream.”

More than 7,000 gallons of water pour over these cascading red quartzite waterfalls every second.

One of the first intercontinental ballistic missile sites in the United States.

Dedicated to the history of the 1,000 nuclear missiles that once covered the Great Plains.