A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

An abandoned saucer-shaped monument in the Bulgarian mountains.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

Two distorted Romanesque columns hold aloft a mine cart in honor of laborers who died during WWII.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

Space-age monument to an early 20th-century uprising.

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

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

A forgotten and crumbling Yugoslav monument to the victims of fascism.

This brutalist monument is inscribed with 9921 names of Yugoslav partisans who perished during WWII.

Yugoslavia's biggest underground airport lies in ruins.

Structure built from the skulls of vanquished foes.

Serbia's master of striking memorials erected a forgotten, hidden gem in the hills outside a tiny village.

Curious carved stones and bird-like wings are a symbol of Serbian resilience and freedom on the site of a WWII massacre.

This symbol of Yugoslav liberation decorated with 620 carved heads of mythical creatures is now a forlorn relic of another time.

An abandoned monument remembering the "Pančevo Holocaust" now stands as a shadow of its former self.

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

Built as an anti-fascist tribute, this surreal Yugoslav memorial became an unwelcome symbol after the Croatian war for independence.

Croatia's towering concrete blossom grows from the site of a World War II concentration camp.

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

Abstract monuments express sorrow and resilience at the site of a horrific massacre in Nazi-occupied Serbia.

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

These warring psychedelic crags commemorate an unsuccessful military operation.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.