An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

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

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

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

Down a cobblestone alleyway is a museum dedicated to Romanticism, with a secret garden.

Site of a classic 19th-century physics experiment to prove the earth is rotating.

A surrealist timepiece by the artist of melting clocks.

France's national museum of scientific and industrial instruments.

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

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

This modest marker near Notre Dame identifies the very center of Paris.

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

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

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

This smaller cousin of the Forbidden City has gone from ancestral sacrifice to tourist's whispers.

This black church sits alone among a field of lava rock.

This tiny museum's sizable collection is jammed into a former underground public toilet.

This elegant arc of a waterfall marks a religious turning point.

The most powerful waterfall in all of Europe.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

Rising from the sea like a stone monster.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

One part local history, 99 parts gruesome haunted house.