Pitié-Salpêtrière was the dumping grounds for women who received the dreaded diagnosis of "hysterical."

Ancient paintings known as the "Sistine Chapel of Cave Art."

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

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

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

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

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

Indents in the pavement are all that remain from a grisly death machine in Paris.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Rumored to have been frequented by Vincent van Gogh, it's the only remaining genever producer in the Hague.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

Take a stroll through the hellish grotesques of Hieronymus Bosch in this elaborate Netherlands church.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

A unique collection of gilded age mechanical pianos.

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

Hidden within a Netherlands crater is a stone bed that lets those who lie in it see the sky as a curved surface.

The Bloemen Route, or “Flower Route”, stretches 25 miles through prime Dutch tulip country as a result of “tulip mania,” the world’s first economic bubble.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.