The fairy tale castle of the "fairy-tale king."

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

This tangled English forest looks like something right out of a fairytale.

Catacombs turned marketplace.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

An unusual round church in London with a Templar past.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A student driver's nightmare.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

Famously misunderstood wonder of the ancient world

Banksy gives themself artistic license with this piece of London street art.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

The sign at the garden gate reads: "These Plants Can Kill."

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

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

A kaleidoscopic warehouse-maze of handmade neon signs.

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.

One of a series of sculptures making a statement about sea-level rise in the United Kingdom.

A striking statue commemorates the men who worked underground in Kingshill and Allanton.