A submerged village appears when dam levels drop.

The stunning interior of this Gothic church is covered in ornate gold details.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This small chapel is built of human bones and decorated with a golden skeleton.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A landscape decorated with enormous skull sculptures.

This remarkable prehistoric town is full of watchtowers and houses that have withstood thousands of years.

This ancient fort has been a great insight into the Roman presence in the region.

This tunnel was built in order to protect the village of Daroca from flash floods during rainy seasons.

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.

An untouched lava tube accessible to the adventurers.

This 18th-century project to build the world's tallest gravity dam was never completed.

This historic electric train has operated with regularity since the early 1900s.

Tower that was a frequent stop on the travels of King James I.

The remains of this misplaced church were moved here stone by stone.

The tallest tower in Cáceres's Old Town.

A prehistoric cave in Spain contains paintings dating back to the Ice Age.

This 15th-century aqueduct with distinctive pointed arches was used for irrigation in the Vinalopó valley.

A road that winds through this natural cave is the only way to access the small, appropriately-named village of Cuevas.

This cave was the former seat of power for two brothers who ruled together as kings.

A solitary lighthouse in Spain was an inspiration to the great Jules Verne.