This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

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

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

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

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

The largest catacomb system in the world.

This attraction was abandoned after the Chernobyl disaster.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

This beautiful natural train tunnel is said to grant the wishes of visiting lovebirds.

One of the longest wooden benches in the world snakes around Geneva's Treille Promenade.

A symbol of friendship between the mountainous regions of Switzerland and Bhutan.

The world's longest and deepest train tunnel.

A once-thriving hotel in the Swiss Alps couldn't compete with climate change.

Traversing steep Alpine slopes, this engineering marvel is one of the longest and highest funiculars in the world.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

A historic observatory precariously perched at the "Top of Europe."

This is not only one of the oldest collections in Europe, but also possibly the most beautiful.

The alpine falls where Sherlock Holmes apparently met his demise can actually be visited.

This lovely little bridge hidden in a Switzerland gorge is essentially a fairytale.

A breathtaking bridge that crosses a vast gorge over a river's torrents, and has a tale of a devil architect attached.

Large Hadron Collider and the Birthplace of World Wide Web.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

This amazing pedestrian suspension bridge in the Swiss Alps would give Indiana Jones nightmares.

Caves famous for the dragon-slaying saint who lived there.