The oldest arboretum on the Dalmatian coast doubles as the gardens of Kings Landing in "Game of Thrones."

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

The remains of a sunken military ship wreck visible through clear water.

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.

This Vietnamese hell cave lets visitors take a walk through a devilish underworld full of demons.

This cliff-face port is considered a masterpiece of mining engineering.

A former mining village that now operates as an open-air museum.

A collection of sculptures that explore what's at stake when nature is thrown out of balance.

This one-of-a-kind archeological site is home to strange prehistoric ruins, the original use of which is still a mystery.

Stalactites and stalagmites in a beautifully lit cave.

At an estimated 3,800 years old, this olive tree is one of the oldest on earth.

Mysterious tombstones thought to be remnants of Atlantis.

Once the legendary capital of the Dacian Kingdom, this city has been reduced to mere ruins.

A Romanian church built from one single oak.

A stunning 18th century pharmacy and medieval chemist's collection.

This enormous abandoned prison was once dubbed the "Bastille of Romania."

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

Known as the Hintz House, this medieval pharmacy has been an apothecary's haven for nearly 450 years.

Even drowned in an ocean of toxic waste, the remnants of this Romanian village stand tall.

One of the oldest churches in Romania is believed to have been built on the site of a pagan temple.

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.