An ancient stone fortress considered by many to be the eighth wonder of the world.

Mozart's skull may be held in this collection, but definitive proof continues to elude scientists.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

A landscape decorated with enormous skull sculptures.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A small church ornamented with medieval erotic sculptures.

"Alleys of Stone" form natural mazes in Spanish natural park.

Houses are tucked between, on, and underneath giant boulders.

A battle between nature and architecture in the Cambodian jungle.

This dramatic sea spire is home to the world's rarest insect and is part of the lost continent of Zealandia.

One man's artistic vision is a small town government's legal battle.

The ancient tomb acts as a calendar that keeps perfect time.

Abandoned city hidden from the world by tropical forest and isolation on the coast of Kenya.

Ruins of the Crusaders' headquarters.

The Syrian headquarters of alleged hashish-smoking assassins.

A 1,500-year-old ghost settlement is slowly fading away.

What is left of the pillar of Saint Simeon, the voluntary martyr who climbed the column to give his sermons, remaining perched there for thirty-seven years.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

A Belgian self-built tower inspired by the Bible and ancient civilizations.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.