This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

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

This incredible stone temple is a monument to death, victory, and fantasy architecture.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

A French artist's vague warning hangs over Belleville.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

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

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

This Parisian café sticks almost exclusively to an ethos of reuse.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

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

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

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

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

A unique seaside cave where Aleister Crowley faked his own death.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

Rodin's famous depiction of Dante's 'Inferno', amidst a sculpture garden of many of his other works.