This spaceship-like Serbian monument reaches for the stars in celebration of the fallen fighters of fascism.

This memorial park stands on the site of one of the largest mass executions of the Second World War.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

A forgotten monument to Yugoslavian freedom.

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

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

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

A wunderkammer of gold and silver reliquaries and ancient saintly bones.

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

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

Longest fortress system anywhere in Europe.

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

Humble beginnings for one of the world's most famous scientists.

This huge metal monument is slowly being stripped to its concrete skeleton.

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

An ethereal glowing blue ocean cave in Croatia.

The monument honors the mountaineers who were part of Europe’s best anti-Nazi forces.

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

This massive subterranean fissure is known as the "underground Grand Canyon."

The Slovenian architect designed many landmarks in the capital city, including his own dream house.

An ancient chamber filled with wonderful rock art and a Neolithic carving of a human face.

A replica of the decorated wooden pillars Viking sailors threw overboard when finding new places to establish a settlement.