The castle still holds traces of the abandoned Roman fort it was built atop.

England’s ancient oak tree has such an impressive girth, people have been hosting parties within the hollow trunk for centuries.

A swath of France so devastated by war it is still forbidden to go there.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

A charming Spanish village sits atop this natural limestone overpass.

The bizarre headgear looks like it was made for a fool, not a king.

The sinister ruins of one of the worst dam failures of the 20th century lie in this astonishing alpine setting.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

Dictionary Johnson’s favorite feline.

The wooden telephone box hidden away in London's Piccadilly was the original prototype of the iconic kiosk.

The Tudor-style cottage in the middle of the square is not quite what it seems.

Black cat statues guard this temple-like Egyptian revival factory.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

Follow the original medieval paths that wind through this intriguing section of the city.

A 17th-century church is nestled within the walls of a 15th-century ruin.

With lush plants and flowers, huge trees, ponds, and hidden monuments, this place feels a bit like discovering Narnia.

A stretch of land where the sour-sweet vegetable is cloaked in darkness and grows so fast you can hear it crack, squeak, and pop.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

A 12th-century fortress containing some of Berlin's oldest buildings.

This strange building looks like a medieval fortress crashed into a 1960s Brutalist office block.

The final resting place for the remains of 143 Habsburg royalty.

A crumbling island fortress that seems to be covered in a field of stone crosses but is simply incomplete.

This is what trains will look like after the zombie apocalypse.