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

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

One of the most powerful religious centers in the Middle Ages, dubbed the founder of Western monasticism.

Perhaps the most beautiful of preserved saints, with a little help from Paris.

This church sits upon a peaceful hill and a long, turbulent history.

One of the oldest masonic museums in Paris.

The curios of pharmacist and collector Henry Wellcome.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Rebuilt remains of a temple to Roman god Mithras.

Hear the quietest sound from across the dome.

An unusual round church in London with a Templar past.

The most visited, and possibly most controversial, museum in Germany.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The beautiful baroque library of the Hapsburg empire.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

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

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

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Macabre astrological automaton clock dating to the late 1400s.