Imperial palace of Emperor Galerius, the Emperor behind the worst Christian persecutions during the Roman Empire.

This fresco inside a Serbian cave church has been a source of disagreement.

This dazzling Art Nouveau mansion is now home to the Modern Art Gallery Subotica.

A Roman monument to their own civil engineering prowess.

These natural stone bridges are the largest on the European continent.

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

A hidden stream deep in the mountains creates one of the largest tufa waterfalls in Serbia.

The ridged layers that make up this river canyon represent Earth's geological history.

This fresco-covered medieval monastery hangs from the side of a steep cliff.

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

The ruins of this medieval castle on a foggy hill tell the story of a once-mighty empire.

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

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

For over 40 years, this quaint little house has teetered on a rock in the middle of a river.

This memorial park stands on the site of one of the largest mass executions of the Second World War.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

Structure built from the skulls of vanquished foes.

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

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

A beautiful mountaintop mausoleum devoted to a Montenegrin icon can't seem to make everyone happy.

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

This ancient Roman aqueduct once funneled water to Diocletian's palace.

A unique interactive experience of everyday life in communist Yugoslavia—a very different time in Croatian history.

This modern, multimedia museum takes visitors on an evolutionary journey back in time.