A open air theatre built on a cliff by an eccentric British woman.

The ruins of an 11th-century Norman castle with a rare, perfectly circular shape.

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

A unique waterfall that some believe attracts the fairfolk.

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

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

This giant wooden treehouse within a sprawling garden has its own eatery.

Locals use these rock pools and waterfalls for swimming and cliff diving.

Continental Europe's only museum devoted to salt and pepper shakers features more than 20,000 designs.

Possibly the oldest masonry dam in all of Europe.

This exhibition space designed to look like the skeleton of a whale is hidden underground.

A dictator's failed public works project has been reborn as two linked trails through spectacular scenery.

This 50-foot-deep sinkhole created in the 14th century is home to rare plants and fungi.

Abandoned Roman Catholic chapel abused by Satanists before being restored.

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

This unique building in the main square stands out among the city's typically Baroque architecture.

A centuries-old forgotten underworld lies beneath Malta.

The eclectic seaside sanctuary caters to a rather fowl crowd.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

Long abandoned underground complex to keep royals safe from a nuclear war that never came.

Bored potato-guarding Nazis etched their thoughts onto a brick storage building in Copenhagen's Meatpacking District.

A little-known cafe in an old copper bridge tower with 360-degree views of the harbor.