An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This bridge was constructed from the rubble of the infamous Bastille.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

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

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

France's most famous cemetery, with some of its most curious tombs.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Elevated freight railway turned wildly successful urban park.

Try not to get slimed in Tribeca.

This London plaque marks the spot where David Bowie's famous alien made his debut.

Giant, friendly pelicans in Central London, the most unlikely of places.

The final resting place to 300 Victorian-era pets hides inside the city park.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

What was once a true peninsula has now been filled in, causing the water to recede and leaving many streetside "waterfronts" and landlocked "islands."

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

The former site of an all-but-forgotten colonial landmark is now remembered by an often overlooked bas relief.

Tragedy on Little Brewster Island memorialized.