This small chapel holds the mummified heart of one of the heroes of the Greek Revolution.

A sprawling collection of books and manuscripts about ancient Greece that would have put their famed libraries to shame.

Down this Cracovian street resides a plaque with a stark message about the city's air pollution.

A statue commemorating a Polish dog who took his role as man's best friend very seriously.

Romania's triumphal arch looks out over Bucharest.

A celebration of all things tacky, garish, and bizarrely creative in the Romanian capital.

Eastern Bloc nostalgia, anybody?

A striking symbol of the Bulgarian capital.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

A collection of art from Bulgaria's time as a communist state.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

Hidden away in a modern library are the remains of one of the 18th century's most celebrated wunderkammers.

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

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

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

This Parisian café sticks almost exclusively to an ethos of reuse.

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

A museum filled with tiny, adorable versions of the mighty Royal Danish Navy.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

An incredibly well-preserved piece of ninth-century Viking poop.

This network of narrow, medieval passages has the most delightful name.

This 18th-century fort surrounded by a moat was used to store gun powder and ammunition, and now sits in the middle of a large part in Dublin.