Depending on the region's rainfall, this church may be partially submerged.

The largest Roman amphitheater in the Balkans once held over 20,000 people, but managed to lay hidden for hundreds of years.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

The crumbling remains of a once-grand building.

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

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

This World War I fortress is the perfect place to catch a Montenegrin sunset.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

The now-overgrown beach resort was once frequented by Yugoslav military elite.

Dive for drinks at Croatia's first and only underwater winery.

An ethereal glowing blue ocean cave in Croatia.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

A climbing route in the mountains of Italy’s Dolomites, built for soldiers during World War I.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

This narrow fjord-like bay is the largest ria in the Mediterranean Sea.

Now abandoned, the world's first torpedo factory is crumbling into the sea.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

A perfectly preserved hill village where the buildings are painted like white lace.

The world's largest collection of intentionally useless inventions.

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

These delicate sand pyramids look like naturally occurring gothic spires.

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.

An open-air museum in a mountain valley features works designed to blend in with—and disintegrate back into—their natural surroundings.

This Italian foot path winds through the mountains via 52 individual tunnels.