This beautiful natural train tunnel is said to grant the wishes of visiting lovebirds.

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

Moss and stone turn this waterfall into an otherworldly liquid veil.

Just a few miles from Novalja, a strange geological oddity has left scientists baffled.

This picturesque medieval monastery guards a small trove of historic treasures.

Longest fortress system anywhere in Europe.

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

This Croatian fairytale castle is slowly falling apart thanks to years of neglect.

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

Legend has it fairies gathered at the site of this medieval castle.

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

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.

Obscured within a ring of trees, this abandoned World War II relic hides on a German hillside.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

When Croatia became independent of Yugoslavia, the splintering governments left behind these concrete tunnels.

Beautifully carved tombstones fill this unmarked graveyard, uniquely situated near the village's famous stone wine cellars.

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

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

Ride in 1960s style on the private luxury train Marshal Josip Tito used to travel around Yugoslavia.

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

A Red Cross memorial museum at the site of the Niš concentration camp that operated for four eventful years during World War II.

For over 40 years, this quaint little house has teetered on a rock in the middle of a river.