A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

Ancient paintings known as the "Sistine Chapel of Cave Art."

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

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

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

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

This museum houses an imposing skeleton army comprised of creatures great and small.

A haunting collection of the vanished and disappearing natural world.

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

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

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

It's believed Matilda Fitzwalter's life was the basis for the famed literary figure.

It's believed King John of England stayed at this 13th-century castle before riding off to sign the Magna Carta.

Ancient human remains unearthed around the iconic monument.

This hill nestled in the Scottish lowlands was a ritual site for over 4,000 years.

Children's hospital in London that operates on royalties received from Peter Pan, which J.M. Barrie signed over in 1929.

A headstone notes where the most famous of Robin Hood's legendary Merry Men is reportedly buried.

6000-year-old site covered in more than 50 megaliths.

You can crawl inside this atmospheric 5,000-year-old tomb.

This stack of stones honors a murdered 18th-century woman.

Gutted during the Liverpool Blitz, this architectural husk has been left destroyed in honor of the dead.

This witch statue remembers a time in England's history when fear trumped truth.

Europe's largest prehistoric mound – burial site of a legendary king?