This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

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

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

The history of radiation is on safe display at the foot of a radiation science laboratory.

Statue of death tucked in the University of Medicine courtyard.

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

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

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

This massive library holds what was once the largest book collection in the world.

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

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

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

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Where's a guy to go after a long, hard day at work?

The Tudor-style cottage in the middle of the square is not quite what it seems.

The remnants of a strange stilted building on rails can still be seen at low tide.

A relic from one of London's worst 19th-century slums.

This early version of the guillotine was used to execute the man responsible for its construction.

Old Tudor home moved on thick iron rails to a new spot.

One of Bristol's best-hidden gems has ties to Lord Byron, whence it became the nation's first reformatory school for girls.

This WWII aircraft museum presents its wrecks like taxidermy, complete with recreations of the crash sites.

At just 51 feet and 10 inches long, it's the shortest street in England.