In the hinterlands of Serbia's capital, a giant reflective mushroom houses an aeronautical history of the former Yugoslav republic.

The oldest church in Serbia was also the ecclesiastical seat of the region during the Middle Ages.

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

A maze of underground tunnels beneath one of the most beautiful forts in Serbia.

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

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

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.

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

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

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

Despite being pillaged and destroyed a number over times down the centuries, this historic church still sort of stands.

Religious perseverance and cultural coexistence manifest in an architectural gem that multiple wars couldn't topple.

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.

No one knows who built this strange cave of worship or exactly why.

This once-derelict building is now one of the most beautiful bookstores in the world.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

Conspiracy theories and occult legends surround this mysterious natural rock formation.

The romantic botanic tunnel feels like a well-kept secret.

The interior of this Serbian royal family's mausoleum is covered with exquisite mosaics.

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

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

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