A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

A mechanized clock where a man fights off a dragon, crab, and rooster.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

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

Paris' linguistic guide to the international language of, yes, love.

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

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

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

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

Notorious artist squat renovated into legal studios.

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

The ruins of a once-grand mansion in Northern Ireland are now thought to be haunted.

This World War II relic let Allied pilots know they were entering neutral airspace.

It is said a heartbroken man visited the gap every day to stare blankly out at the sea.

Wander among the abandoned ruins of this once-powerful medieval town.

The rusting hulk of a hand-powered, nearly 160-year-old submarine abandoned in 1869 due to the ravages of decompression sickness.

A huge, bustling local market in Panama City.

The ruins of the first Spanish settlement in Puerto Rico.

This small fort played a huge role defending Puerto Rico’s capital city.

An ancient chamber filled with wonderful rock art and a Neolithic carving of a human face.

Huge standing stones mark a site of megalithic mystery.

The world's toughest modern Christian pilgrimage leads directly to the gates of Hell.

An unusual manor of stunning beauty, born out of a crippling disease.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.