This church sits upon a peaceful hill and a long, turbulent history.

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.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

A fortress on this island housed the mysterious prisoner known as the "Man in the Iron Mask" for more than a decade.

The handiwork of a underdog clockmaker who solved an impossible problem for an Empire, and forever revolutionized seafaring.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

Pop culture has helped to keep this iconic British building from being destroyed.

65 million-year-old chalk outcroppings mark the end of the Jurassic Coast.

This cathedral's stained-glass patchwork of psychedelic colors and shapes was put in place long before the swinging 60s.

A medieval replica of King Arthur's legendary table, the Round Table hanging in Winchester Castle was decorated by Henry VIII.

A rare labyrinth-style path carved into a historic hill.

Ask nicely, and stewards of a centuries-old charitable tradition will give you free bread and beer.

The biologist's fossilized headstone was meant to reflect his love of nature. Its, ahem, unusual shape is probably just a coincidence.

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

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

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

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.

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