An archeological treasure trove stumbled upon by a couple of children.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

The remains of an encyclopedic sculpture garden later used as an internment camp.

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

An outsider folly near Madrid.

Seaside ruins of a settlement that date back to the first century B.C.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

A Spanish artist builds his own castle.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

This century-old ruined temple was reborn as "The Church of Skate."

Now a pile of ruins and rubble, this was a lovely mountain town as recently as 1960.

This religious complex carved into a cliff is steeped in legends of miraculous stags and the Holy Grail.

The oldest Roman lighthouse still in use.

A living art gallery painted on a canvas of Monterey pine trees.

On La Gomera, "Silbadors" communicate in a 4,000-word language of whistles.

The earliest known map to show America, discovered by accident at a Paris bookshop.

Mine shafts and hard pastries await visitors at this massive mountain of salt.

One of the largest ossuaries in Spain is packed from floor to ceiling with bones.

"Alleys of Stone" form natural mazes in Spanish natural park.

Stunning Roman aqueduct used for 1900 years and still standing.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.

Numerous sculptures set along hiking trails symbolize and idealize the relationship between man and nature.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

This awesome Spanish castle is so fantastical it was actually used on Game of Thrones.