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

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

Where the lovelorn find a home for their sentimental keepsakes.

A musical instrument played by the sea.

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.

A massive cross stands as the sole resident of this water-locked Crimean crag.

This vineyard was the site of the infamous Charge of the Light Brigade.

The saltiest lake in all of Crimea is also the pinkest of the pink and teeming with life.

Over 300 wood sculptures depicting characters from Slavic, Greek and Western folk tales fill this magical garden.

One of the cave cities of Crimea, built by the Goths in the sixth century.

A castle perched precariously over the Crimean Sea.

A massive cave once a secret military base is now home to thousands of bats.

On the outskirts of the small village, an abandoned grassy field glitters thanks to the white stones of an ancient structure.

Founded in the 4th-century, the town of Pernik plays host to the Surva Carnival⁠—a magnificent display of masked Kukeri dancers.

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

Not far from a popular beach, an unfinished, abandoned mansion for Bulgaria's last communist dictator.

One of the largest mines in Bulgaria is now home to a vast museum more than 100 feet underground.

These natural cliffs look like they are a part of an old castle complex.

Rock carving created 1,300 years ago 75 feet off the ground.

An unfinished complex built for children from around the world sits abandoned on the Black Sea coastline.

Ruins of an early Roman Christian church dating back to the 4th to 5th centuries.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

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