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

A museum of carnival attractions where you are invited to ride the rides.

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

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

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.

Notorious artist squat renovated into legal studios.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

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

The largest collection of handbags in the world, the oldest of which were used to carry Bibles, primarily by men.

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

Amsterdam's Red Light District leaves little to the imagination.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

A beautifully eclectic mix of architectural styles.

The attic of a four-century-old canal house hides a clandestine church.

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

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

The world's only museum devoted to the wonders of fluorescence.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

The walls of the iconic dome are hollow and have a secret stairway.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.