It leads to a former hospital’s old root cellar.

Former self-sufficient mental institution now a planned community.

A subterranean world of tunnels links several buildings of this rare 19th-century asylum.

This tree was warped centuries ago to serve as a botanical wayfaring tool.

A legal loophole makes it possible to get away with murder within this 50-square-mile section of Yellowstone.

Where the line between entertainment and aerospace blurs.

A former taxidermist has turned his old shop into a folk art mecca.

This gracefully curving formation looks like a massive wave that was suddenly turned to stone.

A blank headstone topped with a pile of pennies marks the final resting place of the infamous assassin.

The pioneer of psychoanalysis spent the final year of his life here, still seeing patients on that famous couch.

A house of bones — but nobody is quite sure to whom they belong.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

A European-style bath house in Chicago.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

This pair of small sea rocks has been "wed" using rope and ancient Shinto tradition.

See six states, pickled freaks, rocks, and antiques.

The prototype for all Nazi concentration camps.

The city is full of whimsical portals to another world.

America's greatest forgotten garden and the former stomping grounds of Son of Sam.

Reclaimed by nature, the ruins of Doodletown, New York are remnants of a town consumed by a state park.

Willy Wonka would love this weird half-a-home.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

The behemoth beasts engaged in an epic battle is the second-tallest statue in the contiguous United States.