London's old-school healing garden.

One of the world's largest collections of pathological specimens.

A little slice of Japan and its aesthetics in London's Holland Park.

A mysterious artist-run cabinet of curiosities and library.

The final resting place to 300 Victorian-era pets hides inside the city park.

An incarceration museum on the spot of possibly the oldest prison in England.

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

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

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

A kaleidoscopic warehouse-maze of handmade neon signs.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

Relics from as far back as the 16th century are on display in a city known for its playing card industry.

A Cold War command center is hidden under an idyllic countryside.

Descend into the tunnels to experience the life of a coal miner.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

A Museum of Psychiatry in a still-operating mental institution.

This abandoned Belgian fortress is purposefully being left to nature.

Hiding the longest subterranean river known in the world.

This ghost town in Belgium will lose its street art when it ceases to exist.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Perhaps the most spectacular grotto along the Algarve coastline.

This star-shaped military outpost is now simply trying to protect itself from neglect.