The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

Enter the cabin of a life-sized Hindenburg replica.

The site of one of history's most indelible and horrific tragedies.

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

Soaring over the Niagara Whirlpool since 1916.

This massive airship factory is so large that it has its own indoor weather.

The crash of this great airship signaled the beginning of the end for dirigibles.

One man has installed bathtubs into the Utah desert floor to harness the powers of a natural hot spring.

The clock that sets them all.

An annual festival celebrating Colorado's most famous frozen corpse.

Inspired by a music box, a small town Vietnam vet carved an entire carousel full of animals by hand.

A stark reminder of the huge nuclear weapons plant that once stood on the site and its effect on the surrounding area.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

This underfoot portrait is the work of a disgruntled painter inspired by a tragic poem.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.

A museum devoted entirely to the rattlesnakes and snake-related art.

While most of the games in this arcade take quarters, that would have been a small fortune when they were made.

This museum started as a collection of Manhattan Projects and continues to add exhibits as they are declassified.

A whimsical monument marks the highest point in Kansas, not that you could tell by the looks of it.

A funhouse dummy that turned out to be a real life mummy, Elmer McCurdy is an urban legend come true.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

A late sculptor's last project was to turn this abandoned cement factory into a castle-themed amusement park.

Erosion and time have created a naturally-formed water park.

The oldest university museum west of the Mississippi retains its 19th century feel.