Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

A speakeasy takes on Chicago's drinking culture.

These brass bunnies honor the rabbits that dominated the no-man's-land around the Berlin Wall.

A 140-year-old castle with underground caves hidden in San Francisco.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

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

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

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

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

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

Indents in the pavement are all that remain from a grisly death machine in Paris.

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

Statue of death tucked in the University of Medicine courtyard.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

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

Stroll through retro Paris while shopping for old postcards and discarded doll heads.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

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

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

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

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

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

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

Macabre astrological automaton clock dating to the late 1400s.