An underground city of salt.

UNESCO-protected ancient burial ground.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.

Revitalization efforts converted a former U.S. military heliport into a sprawling urban park.

An ongoing medieval tradition of communal pig husbandry is honored with a handsome granite sculpture.

This remarkable museum sprung from one of the most important prehistoric archaeological sites in the world.

The most elaborate of 12 medieval arched doorways to the old city of Burgos.

The former home of a conniving 17th century politician is now a high-end hotel.

1,300 chamber pots and their eccentric collector.

The gaunt visage of this angular Christ giant is enough to put the fear of God into all who see it.

This charming, medieval walled village is Spain's first "book town."

Remarkably intact Roman stone fortifications have encircled this Spanish city for centuries.

Devastated landscape used for hundreds of years by the Romans as their primary mining site.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

A historic Christian shrine nestled within a spectacular natural cave.

A wonderful collection of fossilized dinosaurs and other creatures that roamed the landscape millions of years ago.

The atmospheric ruins of a historic church can be found on a hill above the city of Oviedo.

Two large posteriors in one giant statue.

The much-loved protagonist of famed Argentinian comics can be found sitting on a park bench.

The surviving remnants of a destroyed medieval church now stand in a public park.

See replicas of Europe's most famous cave paintings and even some of the animals that feature in the art.

This whimsical statue dumps water on its head to symbolize knowledge flowing into his brain. Or maybe booze.

A giant bug impaled on a 75-foot-tall needle.