A poem by Arthur Rimbaud is inscribed on the wall of a street that, while it is only one block long, plays a key role in multiple novels.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

A museum dedicated to linguistics, from how babies learn to talk to endangered and extinct languages.

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

The video game-themed street art first popped up in the French city.

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

The site where two doves fell in love.

The narrowest street in Paris.

A surrealist timepiece by the artist of melting clocks.

The symbolic center of Ireland, this summit also offers panoramic views of the countryside.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

Of course Salvador Dalí lived in a castle...

Kissing the ass of this stone lioness has become a rite of passage in the city of Girona.

Designed by Gustave Eiffel before his famed tower.

Rare wooden escalators lead deep down into an otherwise staggeringly monotonous tiled tunnel.

Hidden along this old street in Antwerp is a surreal monument of a bronze arm sprouting four hands.

This statue dedicated to the story of a Flemish boy and his dog was relatively obscure in Belgium, but a cult sensation in Japan.

This small corner bar is home to a rare 1930s dance organ that still plays tunes for one Euro.

According to this bar, God gave an “11th commandment” to Antwerp: Thou shalt drink beer.

To enter this cluttered-yet-cozy sanctum of Belgian brews, ring the bell and tell the gatekeepers you've come “to taste beer.”

An open-air sewer system that was covered piece-by-piece over 300 years.

There are hundreds of secret WWII bases hidden in British forests. Built to fight a Nazi invasion, they remained unknown for decades.

A former top secret nuclear fallout shelter now operates like a hotel stuck in the Cold War.

These crumbling Latvian forts make for some haunting seaside ruins.