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

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

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

A self-proclaimed libertarian micro-state on a tiny bit of disputed territory between Serbia and Croatia.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

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

Longest fortress system anywhere in Europe.

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

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

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

Yugoslavia's biggest underground airport lies in ruins.

An ethereal glowing blue ocean cave in Croatia.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

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

Troublesome students were detained in this tiny graffiti-covered university jail.

This little gem in the Gulf of Riga has a very rich heritage and distinct culture.

A wooden replica of France's famous tower.

The oldest continuously operating pharmacy in Europe.

Hundreds of small crosses have been carved into the bark of the trees outside this small Estonian village.

This striking memorial is one of Estonia’s most controversial Soviet leftovers.

A decommissioned submarine base makes a great space for graffiti art.

The gutted remains of this Estonian mansion are a monument to a tragic love.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.