This elegant arc of a waterfall marks a religious turning point.

The second-longest continuous wall on the planet protects a hidden secret in the deserts of India.

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

Part bookstore, part café, and part forest.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

When ecosystems collide in the arid Southwest.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

A salty red wasteland in Tanzania is a breeding spot for endangered flamingos.

Venice's island of the dead.

Inspired by "The Starry Night" this Dutch bike path turns into a glowing work of art each night.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

The mysterious round rocks of Schooner Gulch.

Real bones which are said to have belonged to a Polish dragon.

The largest cave shaft in the world is home to thousands of birds and popular with BASE jumpers.

A mecca for India's Jains.

A Beaux-Arts triumph rises from decades of decay to become the heart of a new innovation district

A hard-to-reach oasis in a desolate corner of Death Valley National Park.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

Catacombs turned marketplace.

The longest living non-clonal organisms on Earth.

This neon blue river gets its color from a unique mix of bacteria and volcano minerals.

"The most colorful grottoes of the world.

Fire meets ice at the southernmost volcano on Earth.