Hikers can still stroll beneath the long conveyer of this abandoned mining facility hidden in a West Virginia river gorge.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

Since it formed millions of years ago, this cave system has been a sacred burial ground, a Prohibition-era speakeasy, and the center of an amusement park.

The remains of a foundry and old blast furnaces destroyed during the Civil War are preserved in this central Alabama park.

In 1911 this intersection was called "the heaviest corner in the South," an outlandish claim that only grew wilder over the years.

The metal spire on the roof of this tower was intended as an airship docking station, but it was never actually used.

In Rickwood Caverns, visitors can travel hundreds of feet underground and see beautiful formations unique to the region.

A miniature city built by a single hunchbacked monk.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

The mysterious large white cross visible from the runway is a memorial to a massacre during Spanish Civil War.

This line of 12 tower mills described in the story of Don Quixote is among the most iconic landscapes in Spain.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

The world's largest wooden structure.

The final resting place of the great navigator, or maybe his brother.

Spain's largest bullring offers a unique glimpse at architecture and history.

The oldest Roman lighthouse still in use.

The facade of this 16th-century building is decorated with carvings of 300 seashells.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

According to tradition, King Phillip II supervised construction of the seat of his empire from this seat carved into rock.

This influential Renaissance-era library was once the haunt of kings and monks.

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