A unique beach made of a myriad of multi-sized pebbles.

A cemetery and the town it served sinks beneath the sea during the volcanic birth of Mt. Vulcan.

An abandoned Cold War missile radar site.

An ancient city hidden in the heart of the Sierra Nevada mountains.

Enchanting cave with a river crashing through the roof.

A long, winding trek rewards you with a gorge so captivating it inspired a painting in the Tate.

A three-tiered waterfall plummets from a mountain cave with amazing views over the countryside.

A massive underwater sinkhole made famous by Jacques Cousteau.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

A boat ride through utter darkness, lit only by headlamps, reveals an emerald green pool locals believe is sacred.

270 million year-old forest of stone.

A bright turquoise river cascades beautifully down stepped terraces in southern China.

This wondrous waterfall rushing down a green-covered mountain wasn't discovered until 2010.

Moss and stone turn this waterfall into an otherworldly liquid veil.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

An avant-garde artist is survived by his seaside garden.

Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

The abandoned ruins of a beautiful medieval castle just outside Barcelona.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

Picturesque ruins once held off mighty armies.

Two well-hidden huts let animal lovers spend the night among the bears, wolves, and other predators of the forest.

A breathtaking flower tunnel bursts with beautiful golden blossoms.

In Hong Kong, a fairytale flower tunnel is hidden within the gardens of a public housing complex.