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

Oh, just a motel on the edge of the desert decorated with thousands of clowns conveniently located next to an abandoned graveyard.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

The superstar of Cold War nuclear bunkers has been featured in countless films but is now barely operational.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

The oldest Italian café in Boston, this spot also serves as a veritable museum of vintage coffee ephemera.

A very classy 1920s-era bar right in Grand Central Station.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

This historic London residence was once the womb of Scientology.

A monolithic monument in Greater London.

It's a mystery why these remains were found with no traces of their bodies in sight.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

The Florence Nightingale Museum is home to the famous nurse's most treasured possession: her beloved pet owl.

A flourishing garden with pigs, donkeys, goats, rabbits, guinea pigs, chickens, ducks, and sheep.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

Scattered throughout London are ancient remnants of the city's former bounding wall.

London's old-school healing garden.

Even after the church tried to wipe the practice out, this pagan festival lives on each year in a small Scottish village.

This early version of the guillotine was used to execute the man responsible for its construction.

Remnants of the 16th-century defensive wall still stand unassumingly within Edinburgh.

This unchanged Victorian park is rumored to have been the inspiration behind Peter Pan's Neverland.

Eyam took steps to quarantine themselves and keep the plague from spreading.