A line of abandoned, alien-like fortresses dot the mountains of North Italy.

The last planned Soviet city was built for the former residents of Pripyat after the Chernobyl disaster.

The tallest residential building in Africa is an unsettling Brutalist monolith.

This magical space partly designed by Antoni Gaudi is one of the best examples of romantic gardening in the Mediterranean.

Exotic feline breeding compound and conservation center.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

On Japan's Tashirojima Island, cats are king.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

The island of Lanai in Hawai'i is a paradise for cats and cat lovers.

Island wonderland for communist autocrats.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

Double spiral staircases are not unheard of, but they are very rare.

A pair of connected skyscrapers form this symbolic gateway.

Museum preserving torture methods from the past.

This exclusive resort has completely covered a tiny Balkan island in a 5-star warren of guest rooms.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

The resting place for anonymous victims of the Danube's dark waters.

Macabre museum devoted to historical Viennese murders.

Ever hear of the Milazzo Cage?

The first Russian Orthodox church in the Catholic city of Rome in almost a thousand years.