This abandoned Croatian stronghold never saw a great deal of conflict but it is still a beloved relic nonetheless.

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

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

Longest fortress system anywhere in Europe.

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.'

This medieval castle was reconstructed by Carlo Scarpa.

A settlement that was stopped in the middle of construction, leaving behind paved roads, curbs, light poles, a stormwater drainage system, and even a basketball court, but no houses.

A little-known park with unusual, half-ruined structures and a mystical energy.

Its frescoes depict the likeness of Marshal Tito, Karl Marx, and Friedrich Engels burning in hell.

This fresco-covered medieval monastery hangs from the side of a steep cliff.

A UNESCO-protected spiritual seat of the Old Serbian Kingdom and Empire.

An unfinished Serbian Orthodox church with 1,389 golden crosses planned to represent the Battle of Kosovo.

A futuristic, brutalist masterpiece that is also strangely prison-like.

This field of half-buried stone crosses was the burial place of a sect of heretical gnostics.

This 3,800-year-old site contains markers used to study the movement of the sun and moon and create a lunar calendar.

A monastery considered a state-protected cultural monument of exceptional importance, founded in the 14th century by Serbian King Stefan Dečanski.

The ceiling of this cavern is dripping with multicolored marble stalactites.

A naturally beautiful, seemingly bottomless deep blue spring.

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

One of the largest single-span stone-arch bridges in the Balkans looks like something straight out of a fairytale.

After witnessing the rise and fall of three empires, this ancient city was finally destroyed by a series of earthquakes.

A 14th-century Serbian Orthodox church that was once converted into a mosque under the much-disfavored Ottoman Empire.

This lonely minaret with an unusual decorative symbol is all that remains of a historic Ottoman mosque.