The tallest sea cliffs on the Southern Hemisphere are a climber's worst nightmare.

Ruins of a 10th century church tucked away deep in a botanical garden.

The middle finger of modernity.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

Island wonderland for communist autocrats.

Medieval town turned hippie commune, once home to the secret foreskin of Jesus Christ.

This one-time health resort was used by aristocrats around the world.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A 16th-century horror show built in a lovely Italian garden.

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

An ancient capital city that dates back 3,000 years old and harbors many surprises.

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

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

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

This centuries-old Italian chapel hangs midway down a sheer cliffside.

This Italian foot path winds through the mountains via 52 individual tunnels.

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.

Renaissance villa and gardens complete with a tormented colossus.

The Pope’s secret escape route.

A modern sliver of architecture in Roma.

A submerged archeological park still holds the wonders of a Roman Sodom.

A sulfuric hellscape in southern Italy.