A wonderland of caves in eastern Iowa.

An underground wonderland in Iowa.

Chilly air billows out from the entrance of an abandoned mine on a steep hillside, providing a refuge for Ice Age fauna and flora.

The remains of a bustling turn-of-the-century park built to showcase the wonders of electricity.

For just a few bucks, this Iowa funicular will let you feel like an 1800s fat cat.

A warning to the weak-kneed: This narrow bridge does its swinging eight stories high.

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

Despite repeated attempts to make it work, this former mining town is now nothing but dust and memories.

The cliff and rock formations are made out of Sioux Quartzite.

Abandoned businesses, homes, and rusted cars are all that remains of this stopover town.

This Wild West attraction is alive with glitching automatons.

A cemetery housing wild west legends in South Dakota.

The highest point in South Dakota contains the ashes of Valentine McGillycuudy, the "Holy White Man."

A striking sculpture built to honor the women of the Lakota and Dakota Nations.

The deserted railroad town had a last gasp as a ghost town attraction before being abandoned for good.

Thanks to a loophole in property ownership, this alleyway has become a cacophonous street gallery.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

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.

The ravine where Jesse James supposedly performed an impossible jump to evade capture.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

A classic theatre located along a desolate Montana road.

Crystal clear, drinkable mountain spring water by the side of the road.

Multiple monuments to a grizzled old mutt that survived the landscape of Butte's treacherous Berkeley Pit.

A once celebrated industrial wonder now lurks in a quiet corner of Flathead Lake.