400 million years of erosion shaped these fascinating seaside caves, which made an appearance on 'Game of Thrones.'

Amazing vistas await visitors to this stretch of coastline.

It is said a heartbroken man visited the gap every day to stare blankly out at the sea.

This windmill was used for well over a century.

A proud bronze billy stands as an eternal symbol of Ireland's oldest festival, where a goat is made king.

Traveling this mountain pass reveals quaint stone buildings, stunning Irish scenery, and a bridge said to grant wishes.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

These imposing walls and towers look more like the ruins of a fortress than a monastery.

This aging storage facility is the world's largest brick warehouse.

An underground city of ancient quarry tunnels hid thousands of Allied soldiers in WWI.

A monument to the thousands of Canadian soldiers who died capturing the French ridge during World War I.

What was once a bustling mining installation is now a bustling hub of contemporary art.

Six turbines towering over a wide road for passersby.

The "stairway to heaven" lookout tower was built to resist weather, arson, and the laws of physics.

A 14th-century fortified keep showcases the masterpieces of an ingenious 20th-century clockmaker.

A collection of weird and wonderful art fills a former houseplant nursery.

Invisible bridge parts the waters, invoking biblical images and preserving the ominous feel of an ancient moat.

The bridges portrayed on EU currency aren't fictional anymore.

Peek through a transparent pyramid and drink in the mountain made of books.

This unique sculpture proved invaluable when it saved a train from careening off the tracks.

Watch the local Netherlands birds from inside this giant eco-egg.

Its town washed away centuries ago, this lonely tower by the sea tells the tale of a mermaid and a curse.

This ghost town in Belgium will lose its street art when it ceases to exist.

A set of 27 bamboo tubes creates an eerie soundscape that changes with the wind.