This World War I fortress is the perfect place to catch a Montenegrin sunset.

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

A tiny church on a man-made island in the Adriatic.

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

A curious cave church carved into the face of a cliff.

These ancient sunken lanes were naturally tunneled into the soft ground by countless footsteps.

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

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

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

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

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Every color in the rainbow awaits.

An enigmatic modern marker left next to a historic Roman site.

An architect transformed this abandoned cement factory into his castle-like workshop.

Possibly the world's oldest rug, this Egyptian relic is woven entirely from ancient cat hair and once carried a mummified human foot.

This scalding hot river was thought to be a myth until one geoscientist made it his quest to study the mystical waters.

This serene, turquoise lake in an extraordinary nature reserve showcases a rare natural phenomenon.

Once part of an ancient international harbor, it's now an all-you-can-eat shrimp buffet for flamingos and other water birds.

Legends of treasure and spirits flow from this this fairy tale-like oasis.

This foolish Victorian sea fort was converted to a deluxe hotel.

This small but lovely sinkhole lake is the last remnant of a great prehistoric water basin.

The abandoned ruins of a failed resort hide on this verdant, picture-perfect island.