Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Pilgrimage site for star-crossed lovers.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Go inside to really appreciate this 500-year-old technological masterpiece.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Venice's island of the dead.

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

Historic medieval fortified city in southwest France.

The world's largest reflecting pool is just two centimeters deep.

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

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

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

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

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

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

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

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

The celebrated eyesore created by starry-eyed sweethearts.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

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

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

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