Croatia's towering concrete blossom grows from the site of a World War II concentration camp.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

This picturesque medieval monastery guards a small trove of historic treasures.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

Legend has it fairies gathered at the site of this medieval castle.

The remains of a sunken military ship wreck visible through clear water.

A musical instrument played by the sea.

Where the lovelorn find a home for their sentimental keepsakes.

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.

An eerie, existential museum dedicated to the author of "The Metamorphosis."

This doorless 20th-century elevator doesn't stop or slow down.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A magnificent collection of imperial armor and weaponry.

An ornate private entrance to the Vienna subway built specifically for the emperor.

The Habsburgs' royal collections of art and wonders.

Handsomely crafted representations of our round planet.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

This historic hotel on Bathhouse Row in Hot Springs National Park has a storied history of gangsters and baseball greats.

Home of the first female Hungarian poet, where her secret writing lay hidden for over a century.

A Romanian church built from one single oak.

A muddy alien landscape that is home to rare species of exotic plants.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.