Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

A surrealist timepiece by the artist of melting clocks.

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

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.

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

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

The oldest stone house in Paris was built by its most famous alchemist.

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

The bar where "The Great Train Robbery" was planned was once a nexus of high society and low morals.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

London's old-school healing garden.

The remains of Crystal Palace Great Exhibition of 1851.

This series of Scottish caves has no clear purpose other than baffling historians.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

360° views of the city plus five floors of optical illusions and hands-on science.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The last municipal pneumatic post system in the world was in operation for over 100 years, and may run again.