Tucked away behind the mansions of Mayfair, this picturesque garden is a hidden London treasure with a spooky past.

This five-star hotel was originally a swanky parking garage.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

A plaque marks the underground site of one of London's "lost rivers."

This London marker celebrates the spot where the world-famous English band was founded.

Construction of Barcelona’s iconic (but controversial) church was finally completed in 2026—a century after the death of its architect.

This small island, a byproduct of 19th-century canal construction, is now home to a charming Japanese garden.

Home to the "Rat King" of Nantes and other wonders of the natural world.

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

Massive puppet-automaton machines created by French artist collective Machines de l’Ile.

A massively oversized measuring tape sculpture sits inside a hidden yard.

Do these monsters look familiar? The gargoyles on this church are all from pop culture.

The sunken structure looks like the victim of a catastrophic flood.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

Nicknamed the "Museum of Horrors," this French anatomical collection has been fascinating visitors for over a century.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

An intricately decorated tiny place of worship.

Underground hospital complex constructed by slave laborers during the German occupation of the Channel Islands.

This gravestone and its inscription inspired a movement that has spanned generations and saved countless lives.

The front of this 17th-century cottage also contains a large, stone face.

Discovered on a shipwreck after more than 400 years, this Renaissance ratter tells a very waggly tale.

Hauled from the water's depths, Henry VIII's flagship is preserved in this capsule-shaped museum.

A medieval replica of King Arthur's legendary table, the Round Table hanging in Winchester Castle was decorated by Henry VIII.

This silent sentry in the crypt below a large Gothic cathedral is often knee-deep in water.