A well-preserved Ancestral Puebloan ruin tucked beneath a desert cliff.

The damming of the Colorado River buried an iconic geologic formation before record-breaking drought brought it back.

A Mars simulation in the southern Utah desert.

A metal ring in the middle of the road marks the exact spot where the Soviet satellite crash-landed in 1962.

This ancient cave is home to a museum, bar, and is filled with fluorescent minerals.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

A miraculous natural phenomenon known as "the spring that breathes."

The old fire tower is one of the last of its kind in the United States.

This angular Dwarven tunnel cuts through a mountainside in Glacier National Park.

A scenic ravine with an astounding collection of rock art created by the Indigenous people of the Great Plains.

The oldest badlands in North America, Makoshika State Park takes it name from the Lakota words for broken land.

The ruins of Theodore Roosevelt's beloved ranch stand in a forgotten corner of a national park named after him.

This beautiful ancient site is dotted with perforated sandstone pillars considered sacred by some Native American groups.

The first declared National Monument in the United States.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

A waterfall 600 ft. inside a mountain, once the bane of gold miners, is now a spectacle of nature.

This large midwestern cavern features impressive rock formations and an underground waterfall.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.