Perhaps the most spectacular grotto along the Algarve coastline.

A unique waterfall that some believe attracts the fairfolk.

A fantastic castle rumored to be the birthplace of King Arthur.

A neolithic dolmen that was rebuilt after collapsing during the 19th century.

These picturesque ruins crumble beautifully into the ocean.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

The largest greenhouse in the world is home to over one million types of plants.

This heart-shaped island looks substantially less lovely after a recent bulldozing project.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

This fountain has a growing (animal) population, and might also be growing in size.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

A giant gleaming memorial named for a coal miner who gave his life to the pits.

A great example of the inventive canal bridges that were deliberately split down the middle.

This medieval manor house was equipped with secret compartments for hiding priests.

A retirement home for soldiers that can trace its history to the Elizabethan era and beyond.

Preserved baths in a Victorian-era spa town frequented by the most famous people of its day.

The lighthouse is on a island which is connected to another island, which is connected to another island, which is connected to one of the largest islands in the world.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.

The highest peak in Wales is said to be the final resting place of a giant killed by King Arthur.

A miniature Italianate fantasy village on the coast of Wales and the set of ITC classic "The Prisoner."

A stunning example of traditional salt production set against a dramatic volcanic landscape.

Park in the Canary Islands renowned for white dunes that contrast with the turquoise waters of the Atlantic.

On this wooded path, a stained-glass window creates a spellbinding forest cathedral.

A sign at the end of the Santa Monica Pier marks the traditional end of the legendary American highway.