The final remnant of the Arkansas zinc industry is this historically protected ghost town.

Kentucky, Tennessee, and Virginia meet at this point in the Cumberland Gap.

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

A memorial to the unknown and unheralded men and women of the Cold War military and intelligence services.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

This ghost town was once a cult-like religious utopian settlement.

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

A recently abandoned psych ward at the end of Sanatorium Road.

This deserted Gold Rush town is home to a Masonic lodge that, strangely enough, still holds meetings.

The overgrown ruins of a once thriving World War I-era copper mine.

The eerie ruins of an isolated abandoned town nicknamed "the Widowmaker" for its deadly gold mine.

An overgrown garden stands as a grim marker of an unrealized dream.

An eerie, decaying ghost town destined to fade into the forest.

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

The short-lived railroad town in central Oregon has been abandoned since the 1930s.

Salt is slowly eating away this abandoned saltworks town in the desert.

One of the most well-preserved temples of ancient Egypt.

In the woods of New Jersey lie the ruins of a munitions village abandoned after World War I and the remnants of a 1920s wooden racetrack.

A local dialect born in the late 19th century is only spoken in this isolated California valley.

This 13th century castle is chock full of ghosts and impossibly rare cows.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

A toxic ghost town sitting atop a massive coal fire.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.