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

Less a museum than a bizarre fantasy world created by artists and engineers.

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

Moonbows over Kentucky.

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

This church houses the “incorrupt” body of its founding Bishop.

Elvis's own personal tropical hideaway.

Destroyed by flood waters, prison now serves as a training ground for armed forces.

Speak to a companion on the other side of the room loud and clear through this architectural anomaly.

What was once a presidential estate is now an exotic menagerie and home to the Budweiser Clydesdales.

A home designed to be on the cutting edge of comfortable, low-cost living.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

A particularly creepy abandoned hospital that sparks interest for lovers of the supernatural.

Paleoamericans built these ancient walls high in the Colorado Rockies as part of an extensive hunting system.

This old train trestle and collapsed tunnel once allowed the railroad to negotiate the steep slopes of the Colorado Rockies.

Air Force Academy Chapel made of 100 identical tetrahedrons works to inspire those of all religions.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

When zealous marijuana enthusiasts kept stealing the "Mile 420" highway marker, the State of Colorado got creative.

The haunted reputation of these abandoned Colorado train tunnels is probably not helped by the terrifying spiked fence.

The largest source of fossilized insects anywhere.

The highest paved road in North America winds its way up Mount Blue Sky in Colorado to an altitude of 14,130 feet above sea level.

This spectacular track has run continuously since 1882.

An architect in Aspen used psychedelics as his muse while building this mushroom masterpiece.

Thanks to a quirk of elevation this gift shop produces magic doughnuts that are found nowhere else on Earth.