An unassuming London park is actually a pilgrimage site for modern clowns.

This network of narrow, medieval passages has the most delightful name.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

The Hanshin Expressway goes right through its 5th, 6th, and 7th floors.

This ruin in a suburban park may be the place where Shakespeare's "A Midsummer Night's Dream" was first performed.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

In Faroese legend, this sinister horse-shaped beast lures unsuspecting passersby only to drown them in the lake.

One of the last umbrella repair shops in Paris upholds the nostalgic art of umbrella making.

This abandoned Brutalist treehouse is a hidden architectural relic.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

The bronzed skull of a beheaded traitor was affixed to the city gate in the 17th century.

This modern labyrinth lies in the shadow of a ruined medieval castle.

The abandoned funicular tunnel was a secret base for the BBC during World War II.

Behind medieval walls in a corner of bustling Palermo is a breathtaking former mosque once inhabited by a wolf-taming hermit.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

An ancient octagonal weather station named for the eight Greek gods of wind.

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

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

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.

A hidden tunnel leads to a medieval queen's shrine buried beneath a parking lot.

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