The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The remains of the medieval wall that once surrounded Paris with ties to the construction of the Louvre.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

The approximate spot where the last Grand Master of the Knights Templar was put to death.

What looks like a normal building is really a hollow facade hiding a subway vent.

The narrowest street in Paris.

Once a 19th-century brasserie, this McDonald's exterior celebrates Alsatian design and the "King of Beer."

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

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

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

A surrealist timepiece by the artist of melting clocks.

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

The heaviest gold coin ever minted.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

A modern-day Lascaux cave underneath Paris.

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

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

This massive library holds what was once the largest book collection in the world.

The shell of a medieval fortress offers commanding views of the area it once protected.

The heroic tale of a remarkable pup who refused to leave her master's side, no matter what.

These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

Amsterdam's former hotspot for public executions and dissections.