A perfect circle of twenty-four mysterious holes dates back to prehistoric time.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

This 1967 experiment in modular architecture was designed to be a new model for urban living.

It may take some time to locate, but it's sure to warm even a heart of stone.

Unlike other abandoned asylums this empty institution welcomes visitors, just don't go in the buildings.

One of the largest-ever mental hospitals now sits abandoned, surrounded by 25,000 unmarked graves.

This abandoned psychiatric hospital once housed more than 4,000 patients in the middle of a quaint New England town.

A newspaper editor turned this abandoned island into a tortoise nature preserve that's now the world's smallest national park.

The remains of a 19th-century school and living quarters are perched atop a mountain surrounded by a thick tropical forest.

Clusters of abandoned buildings hint at the facility's 144-year history with psychiatric health.

For over a century, it was a crucial center of mental health treatment and also the source of many local legends.

An abandoned asylum where patients have been forgotten but their possessions remain.

The final resting place of the Seminole Indian chief who fought against government occupation in Florida.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

This abandoned subway station can still be seen on regular commuter trips.

This abandoned Navy base was transformed into an off-grid alternative living community for thousands of people.

This crumbling UFO is one of only a few remaining "moveable ski chalets" of its kind.

Odd outsider art installations surround a Gold Rush-era ghost town.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

This former luxury resort in Kaua'i is now an abandoned relic.

Four-story concrete hotel never opened to customers.

This ghost town houses the remains of Alabama's old state capital.

Mile-long cave system near Great Smoky Mountains.

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