This mesmerizing medieval monastery-cave complex sits thousands of feet above ground overlooking a valley.

Popular river that runs through the remote Serbian municipality of Leskovac.

This medieval monastery represents an architectural blend of eastern and western European culture.

A sinuous path among steep cliffs creates a stunning sight in southwestern Serbia.

Longest fortress system anywhere in Europe.

This natural monument has an origin story steeped in legend.

The bizarre rocks of Đavolja Varoš are the result of natural erosion.

Gargoyle head that brings good luck.

This little-known, 35,000-specimen collection in Greece is a lepidopterist's dream.

A futuristic, brutalist masterpiece that is also strangely prison-like.

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

This 3,800-year-old site contains markers used to study the movement of the sun and moon and create a lunar calendar.

Stone pillars and a petrified wedding party in the hills of North Macedonia.

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

Former military fort and site of untold horrors during WWII, this island may become the Adriatic's next luxury resort.

A little-known park with unusual, half-ruined structures and a mystical energy.

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

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

Thousands of rusting train cars have been slowly falling apart on the edge of Greece's second largest city.

An islet filled with wooden houses where the open sea meets a lagoon.

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

One of the world's oldest olive trees, thought to be over 2,000 years old.

A spectacular cave and a beguiling lake.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.