This beautiful Croatian fortress is haunted by legends of forbidden love.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

Longest fortress system anywhere in Europe.

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.

Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

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

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

"Unity, Creativity, Beauty."

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

A flamboyant five-story building in Bulgaria resembles a crawling snail.

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

This historic black and white monastery is one of Bulgaria's architectural jewels.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

An abandoned saucer-shaped monument in the Bulgarian mountains.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

A war-torn Olympic relic is being overtaken by graffiti and nature.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

These warring psychedelic crags commemorate an unsuccessful military operation.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.