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

One family's environment-friendly hobbit-house in Wales.

At the foot of a waterfall lies a peaceful swimming lagoon and evidence of over 60,000 years of human habitation.

A castle that was built stone by stone by an eccentric journalist.

Where the lovelorn find a home for their sentimental keepsakes.

One of the deepest blue holes in the world.

Tibetan-influenced mountain fortress in Northern Pakistan.

This complex of vertically-excavated Buddhist, Jain, and Hindu monolithic temples in India's Maharashtra providence illustrates a spirit of tolerance characteristic of ancient India.

Australian Lake set aglow by Noctiluca Scintillans.

Famed architect Antoni Gaudi built this generous thank you gift to a friendly host who housed him during a job.

A humid oasis combines recreation with exploration in a unique underwater cavern.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

The intriguing personal collection of a professional demon-chaser.

Resonant stone, that has been played since prehistoric times.

Tombstones buried in overgrown grass mark the deceased occupants of this abandoned graveyard.

Sites connected to a woman born on a ship and spared by a pirate.

Each year melting snow turns these Austrian hiking trails into scuba zones.

An exquisite tunnel of cascading flowers.

Living trees form the structure of an open-air palace.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

A town church once nearly submerged by the damming of a river is now hauntingly visible as the water recedes.

Keshwa chaca, among the last handwoven Incan bridges, crosses Apurimac Canyon in Peru.