Noirish green neon marks the location of one of the oldest private detective agencies in France.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Shop at the 200-year-old store where Julia Child stocked up on copper cookware.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

The oldest continuously operating mint in the world that has been making coins since the 9th-century.

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

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

The narrowest street in Paris.

This 400-year-old tree is actually an immigrant from North America.

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

Notorious artist squat renovated into legal studios.

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

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

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

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

This demon atop the Notre-Dame de Paris looks utterly bored.

This modest marker near Notre Dame identifies the very center of Paris.

A Saxony castle houses one of the largest and most outstanding mineral collections in the world.

One of the largest numismatic collections in Europe fell victim to a huge theft.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Largely overlooked, this little fountain on Museum Island is a whimsical tribute to a Prussian king nicknamed the “Fatty Flounder.”

Cold war icon and onetime "hole" in the iron curtain.

A haunting contrast of trains that both saved and took the lives of Jewish children in Nazi Germany.