This former maximum-security prison is creepy, sobering, and supposedly haunted.

An abandoned town is hidden in Great Smoky Mountains National Park.

A recreation of the doomed ocean liner in the middle of the Smoky Mountains.

The secret city built by the Manhattan Project.

All that's left of the quintessential "cabin in the woods."

Collection of trolley cars in the woods represent one man's attempt to preserve transportation history.

These disused steel furnaces are now haunting ruins that may one day be a national park.

This public space is speckled with the eerie remnants of a defunct amusement park.

Toxic waste disaster that founded the Superfund program.

This former mining town was named the most toxic town in America.

An eerie, abandoned military base engulfed by nature and graffiti is now home to a local park.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

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

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

This Queens hospital has stood abandoned for almost 20 years after its patients were secretly relocated in the dead of night.

This mouldering abandoned mental hospital was once a center for progressive healing.

A crumbling hospital from the 1850s on Roosevelt Island.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

A long abandoned hospital building on the outskirts of NYC.

The abandoned grounds and derelict greenhouses of this once-magnificent Edwardian estate are now a nature preserve open for exploration.

The site of a tragic massacre that spawned a multimedia franchise.

An unrealized dream to wirelessly electrify the entire Earth.

A mysterious air force base built to resemble a Long Island fishing village.

Beneath the mossy overgrowth covering this once-sprawling campus lies decades of history and the secrets that come with it.