This tiny island protects a number of rare bird species by only allowing visitors to set foot on the beach.

Five miles of underground river link lake to ocean.

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

Bridge that died in war and was resurected.

A tiny church on a man-made island in the Adriatic.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

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

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

An ancient knight and a symbol of the city's freedom.

A full figure 4th century incorruptible saint lies in a glass coffin in Croatia.

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

Gargoyle head that brings good luck.

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

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.

The first military air station in all of Ireland hosted "battlebags."

These engineering masterpieces are a dominant feature of the Belfast skyline.

This massive monument has been telling the time for 150 years—at a slight angle.

Belfast's namesake river still winds below the city center, hidden from sight.

The only monument to name all of the passengers and crew who died on the RMS Titanic.

These barriers stand as stark reminders of Northern Ireland's troubled past.

A museum marks and documents the site of the Titanic's launch.

The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

This Victorian-era public house has set the standard for pub-style elegance for over a hundred years.