This Parisian fountain is a little bit fantasy and a little bit nightclub.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

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

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

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

A surrealist timepiece by the artist of melting clocks.

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

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

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

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

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

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

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

An artist’s underground sanctuary, 40 years in the making.

This limestone cave offers an incredible view of the Río Grande de Arecibo valley.

Invading U.S. troops were first seen from this now-abandoned tower, leading to the Spanish-American War.

The crumbling remnants of this 19th-century quarantine hospital hint at the touristy island's darker past.

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

Legend has it this historic port was a popular hideout and smuggling spot for pirates.

On a small Puerto Rican island, banks of secret naval bunkers lie abandoned and filled with piles of office equipment.

Puerto Rico's oldest rum producer started its 140-year-old business with "a little barrel."

Years of neglect and nature took a toll on this 19th-century lighthouse.

This tiny home was originally a narrow alleyway.

A magnificent waterfall nestled in the heart of the El Yunque National Forest.