The walls of these four caverns are filled with art that dates back to the earliest human presence in Europe.

Among the best preserved megalithic monuments in the Aragón river valley.

The world's largest single-aperture telescope resides in the Canary Islands.

Several petroglyphs are all that remain of an ancient pyramid.

This remote location of this Moorish stronghold means it doesn’t attract many tourists—and that it still has the aura of fear and bravery of the 1300s.

This medieval fortification has weathered the centuries better than any other structure from its era.

A pre-Hispanic pyramid in the middle of a tourist district in the Canary Islands.

Possibly the oldest masonry dam in all of Europe.

The world's most elegant power lines.

Walls of stone rise up from sinkholes caused by underwater erosion.

This unique rock formation is quite the local celebrity, although one day it may come crashing down.

Medieval ruins nestled within a breathtaking swath of Spanish nature.

An abandoned airport in the middle of nowhere.

This Canary island is a quintessential example of nature’s beauty, and its unbridled fury.

These primitive rock paintings include a very beloved depiction of a woolly mammoth.

An accidental trick of light casts the perfect shadow of a pilgrim of the Camino de Santiago against the cathedral wall.

This underwater graveyard commemorates a group of murdered 16th-century missionaries.

This local emblem is the oldest and largest dragon tree in the Canary Islands.

This surreal-looking tree pruned more than 1,000 years ago is still producing olives for oil.

A model solar system adds a celestial touch to this suburban park.

The unexpectedly beloved remnants of a controversial thermal power plant.

Visit a surreal landscape so otherworldly NASA actually used it to train the Apollo 17 crew.

Rare karst landscape eroded from a flat seabed.

Moorish signal station on a stratgic rocky outcrop.