A New York–based physician returned home to Spain to build his own elaborate monument to Christopher Columbus.

An enchanting landscape of ancient sandstone structures eroded into otherworldly shapes.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

This 47-story "M" needed 20 years to be completed

An underground passage originally constructed as an air-raid shelter during the Spanish Civil War.

This house's itty bitty size means no humans allowed.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

This abandoned viewing platform has become a monument to unnecessary government spending.

This architectural oddity is an oasis of green on the outskirts of Valencia.

The blowhole bursts spectacularly right next to the buildings in a medieval seaside town.

An elaborately decorated house sits on an otherwise quiet street.

Built on the foundations of an ancient Roman villa, the unique architecture of this castle on the Catalan coast was used as a set for 'Game of Thrones.'

Immortalized by artists, this church incorporates a medieval lighthouse into its shoreside structure.

Historic medieval fortified city in southwest France.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

A historic Christian shrine nestled within a spectacular natural cave.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Giant topiary dog once played a role in a terrorist bomb plot.

This beautiful spit of land was once the summer playground of the king of Spain.

A set of 27 bamboo tubes creates an eerie soundscape that changes with the wind.