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

One of the largest barracks of the Austro-Hungarian monarchy's military is now an abandoned ruin.

The abandoned military base looks like a post-apocalyptic wasteland.

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

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

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

An homage to the medieval rulers of Bulgaria.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A little-known caravanserai hidden among farmhouses in the Turkish countryside.

Monasteries on rock pillars, once accessible only by frayed ropes.

This ominous Albanian fortress houses tanks and downed planes as a reminder of their victories over Western imperialism.

These warring psychedelic crags commemorate an unsuccessful military operation.

A swan-like monument on Obad's Hill honors those that defended the area from German invaders during WWII.

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

This abandoned Olympic skiing facility still bears the scars of the Siege of Sarajevo.

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

Inside this small chapel tucked away in the forest is one of the most well-preserved Danse Macabre frescos.

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

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

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

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

The mysterious megaliths have enchanted and intrigued visitors for thousands of years.

On this stunning Scottish island, you can walk in the footsteps of dinosaurs.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.