A passage grave used in neolithic rituals.

A Romanesque tower appears when water levels drop.

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

These tourist trap caverns are said to be the former home of a legendary Pennsylvania Hermit.

Bizarre Cavern.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

The wooded estate of the Forest Service employee responsible for D.C.’s cherry blossom trees.

These abandoned waterworks are crumbling into the Potomac River.

Connecticut sites linked to the only trial to ever use demonic possession as a criminal defense.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

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

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

Once a thriving business district, this former shopping area is now an urban ghost town in the heart of the city.