The world's toughest modern Christian pilgrimage leads directly to the gates of Hell.

Once the longest bridge in Ireland, this rusting span sits abandoned and overrun by nature.

The oldest inn in Kilkenny was established by the first convicted witch in Ireland.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.

A museum of carnival attractions where you are invited to ride the rides.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

An impromptu shrine appeared shortly after beloved "Torchwood" character Ianto Jones was killed off the show.

This abandoned asylum in Wales might look haunted, but it's still beautiful.

The decaying ruins of Wales' first asylum for the mentally ill.

A subterranean playground in an abandoned slate mine.

A secret door leads to this cozy dive that sells only “milk.”

An American ghost town hides along a side street in Scotland's capital.

This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

The house where the writer spent his formative years.

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

The quiet field that inspired one of the most famous songs of all time.

An 18th century monument regularly tagged with unsettling graffiti referencing a 1940s unsolved murder.

Follow the original medieval paths that wind through this intriguing section of the city.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

This foolish Victorian sea fort was converted to a deluxe hotel.