The first declared National Monument in the United States.

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

A cemetery housing wild west legends in South Dakota.

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

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 place where the laws of nature seem to have gone completely berserk... but of course haven't.

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

A bizarre house filled with an astounding array of collections.

A number of gruesome unsolved murders have turned this simple home into a morbid tourist trap.

The World's Largest Bull.

Lured here by the promise of tens of thousands in gold, Jesse James started a quintessentially American trend of robbing trains in-motion.

Beating out all other concrete competitors, this massive garden feature's pointy hat has earned it a world record.

A half-mile long and three stories high, this bridge over the Des Moines River Valley mimics a descent into a mine shaft.

A museum chronicling pioneer life constructed over Interstate 80.

This little gem of a museum is a hidden jewel filled with prehistoric treasures.

An ornate Art Deco tile mosaic representing Nebraskan life, both modern and prehistoric.

A brick-paved former section of the historic coast-to-coast highway.

These experimental weapons brought World War II to Nebraska as well as 26 other U.S. states.

This simple home was the beginning of a long journey for the iconic Western film star.

An Englishman loses his scalp to a Cheyenne warrior and lives to donate it to a library.

This massive railroad spike celebrates the 1939 premiere of the movie “Union Pacific.”

These eight mummies are the best-preserved human remains ever discovered in North America.

The abandoned remnants of a little sanctuary for world peace that fell into disrepair.

In rural Iowa, an imported 19th-century windmill overlooks an unlikely enclave of Danish culture.