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

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

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

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

A surrealist timepiece by the artist of melting clocks.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

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

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

The largest medical and anatomical collection in France lies hidden from the public.

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

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

Brussels' favorite peeing boy has a sister.

Medical history with an amazing, if frighting, collection of wax diseases on display.

This Greek temple, open only an hour a day, was the site of a war of tastes between an architect and an artist.

Climb inside an iron crystal magnified 165 billion times its normal size.

Lavish royal estate punctuated with heated greenhouses.

Each spring, a dreamlike carpet of bluebells overtakes the forest floor.

A mysterious artist-run cabinet of curiosities and library.

Hidden beneath the streets of London is a secret subway that only carried mail.

One part local history, 99 parts gruesome haunted house.

A hands-off space for graffiti artists to hone and display their skills.