Museum preserving torture methods from the past.

The history and future of cannabis.

Even France's favorite aquatic son Jacques Cousteau, couldn't get to the bottom of it.

The castle where the Marquis de Sade lived out his darkest fantasies.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

An underground network of massive stone arches and their skylit vaults support ruins of portico structures above.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

The yawning maw of this pagan visage is said to bite off the hands of liars.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Climb to the top of the world's largest seated bronze Buddha.

A cluttered and astounding collection of antiquities and curiosities.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Pop culture has helped to keep this iconic British building from being destroyed.

The remains of the great moral philosopher reside in a university in London.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

While only two of the ancient buildings at this site are actually churches this was one of the earliest Irish pilgrimage sites ever.

A diminutive, thousand-year-old church believed to be the smallest in Ireland.