What was once the second largest steel mill in the US is now a sprawling complex of modern ruins.

400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

A geological oddity formed by two rivers carving out a mass of limestone on both sides.

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

Curious cave that stays a cool 56 degrees all year long.

European castle ruins in an American state park are actually the product of death and grief.

Patrick Dougherty's fantastic living tree sculptures, mind-blowing but temporary.

This railroad overpass is said to be home to a murderous goat-man whose very legend has led to very real deaths.

Home of an evil witch famous within southern folklore.

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

Remnants of a storybook amusement park hidden behind a strip mall.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

An FDR-era tuberculosis sanatorium has stood abandoned in the suburbs of the U.S. capital for over 30 years.

An abandoned quicksilver mining town surrounded by the Big Bend parks.

A Texas-sized particle collider that was abandoned due to its Texas-sized budget.

The superstar of Cold War nuclear bunkers has been featured in countless films but is now barely operational.

This small town Texas cemetery is said to be the burial site of a UFO pilot who crashed in the 1800s.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

An abandoned movie set in the desert of West Texas.

This fast-food outlet is the only space and UFO-themed McDonalds in the world.

Jacksonville's highways rendered this century-old grammar school unusable.

Disney's abandoned animal island is now an overgrown ruin that was almost the coolest attraction ever.

This lab's maddening silence is good for business but bad for sanity.

A collection of full-size movie monsters opened to the public.