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

An eerie, protected forest of old-growth oak trees, many of which are now dead.

This spaceship-like Serbian monument reaches for the stars in celebration of the fallen fighters of fascism.

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

A grand Yugoslav memorial to the group of partisans who fought and died resisting western Serbia’s Nazi occupation.

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

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

Structure built from the skulls of vanquished foes.

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

A Red Cross memorial museum at the site of the Niš concentration camp that operated for four eventful years during World War II.

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

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

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.

The now-overgrown beach resort was once frequented by Yugoslav military elite.

Longest fortress system anywhere in Europe.

When Croatia became independent of Yugoslavia, the splintering governments left behind these concrete tunnels.

Humble beginnings for one of the world's most famous scientists.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

A tower marking the spot where Yugoslavia began its resistance against the invading Nazis stands neglected, but not quite forgotten.

This huge metal monument is slowly being stripped to its concrete skeleton.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

A crumbling World War I fort that is reached through a series of concrete tunnels.