Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

Cat art as far as the eye can see.

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

A melancholy jester sits on the grave of a famous 20th-century ballet dancer and choreographer.

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

The site where two doves fell in love.

A mud statue stands in the dark tunnels, seeming to hold up the weight of the city above.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

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

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

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

One of the oldest medical collections in Europe focusing on rare surgical instruments.

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

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

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

If the tunes of antique organs and musical marionettes don't intoxicate you, the draft beer certainly will.

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

An abandoned NSA listening post on Berlin's "Devil's Mountain."

An eerie, derelict amusement park in Berlin.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.