An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A mechanized clock where a man fights off a dragon, crab, and rooster.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The oldest stone house in Paris was built by its most famous alchemist.

France's most famous cemetery, with some of its most curious tombs.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

The ritual has been performed uninterrupted for nearly 700 years.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

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

The fierce beast perches atop a pedestal marking where the historic City of London gates once stood.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

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

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

Eighty million natural history specimens call this gargantuan museum home.

An unusual round church in London with a Templar past.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

A restaurant and observation deck built in a unique broadcasting antenna.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.