World's first "penitentiary," meant to be humane, drove men insane.

One of the earliest bowling lanes in the U.S. doubled as a sewing school during a time when women had little job opportunity.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

Once in a state of dilapidation, this candy-inspired fortress is now being revived.

Ride a boat through this magnificent underground world, which now doubles as a theater.

Edison's cast-in-place concrete houses were a failure, but way ahead of their time.

This odd Chilean waterfall-cano hotel must be entered via a rope bridge.

An abandoned dollhouse factory.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

Legend has it fairies gathered at the site of this medieval castle.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

Where the lovelorn find a home for their sentimental keepsakes.

The remains of a sunken military ship wreck visible through clear water.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

North America’s largest collection of horological devices and home to a colossal clock with a dizzying array of features.

An indoor miniature village and labor of love for Laurence Geiringer, a model railroad enthusiast.

A local prank turned town icon.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

The only known Futuro house in North Carolina sits along a stretch of desolate highway on the Outer Banks.  .

This family tattoo parlor has been inking religious pilgrims in the Middle East for 700 years.

Submerged ruins of a Neolithic coastal settlement, where houses, wells, graves and skeletons have been unearthed.