Yugoslavia's biggest underground airport lies in ruins.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

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

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

An ethereal glowing blue ocean cave in Croatia.

This Romanian village may have been drowned, but it is long from forgotten.

One of the most controversial statues in Romania is an emperor with no clothes.

Home of the first female Hungarian poet, where her secret writing lay hidden for over a century.

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

The ancient Greek Titan guards this massive dam holding a lightning bolt to symbolize electricity.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A Romanian church built from one single oak.

Check out engineering marvels of the past at this unintentionally retrofuturist museum.

Romania's triumphal arch looks out over Bucharest.

A stunning 18th century pharmacy and medieval chemist's collection.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

Known as the Hintz House, this medieval pharmacy has been an apothecary's haven for nearly 450 years.

Romania's only crater lake with water as pure as if distilled.

A celebration of all things tacky, garish, and bizarrely creative in the Romanian capital.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

This snug medieval lane is one of the narrowest streets in the world.

Even drowned in an ocean of toxic waste, the remnants of this Romanian village stand tall.

A muddy alien landscape that is home to rare species of exotic plants.