This Norman castle has been the scene of assassination plots, religious persecution, and Nazi conspiracies throughout its long history.

A house of bones — but nobody is quite sure to whom they belong.

A winding cave grotto walkway built to provide employment for veterans after World War I.

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

On the coast of Sardinia, a once-great mining village is finding new life as a coastal resort town.

An eerie gravel road full of shards of red bricks leads to the ruins of a deserted factory.

Once one of the largest sites of silver deposits in Italy.

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

Greenery covers the face of a gently-dripping waterfall deep in the mountains of central Sardinia.

Packed with geological formations, an ancient river, and taxidermied seals, this overlooked coastal cave system is worth a spelunk.

Ancient cave tombs known as the "houses of fairies."

This elaborate hole in the ground was built as a sacred site for an ancient civilization.

The titular "little arch" near this Italian resort is one of the most popular diving spots in the country.

Stalactites and stalagmites in a beautifully lit cave.

A striped 12th-century basilica sits in the countryside of Sardinia.

Mysterious tombstones thought to be remnants of Atlantis.

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

This weird, elephant-shaped rock also hosts two ancient tombs.

Windblown rock formations in an ancient Roman quarry.

Crushed coral and crystals give the sand its signature coloration.

Once the hottest nightclub in France, Amnesia now lies in ruins after a 2000 bombing.

Resting on a hill overlooking the coast, these medieval ruins look completely deserted save for their restored chapel.

This remarkable checkered church on a Corsican hilltop is fabled to have been built by angels.

This stretch of beach is the site of a prime watering hole and a primate watchtower.