North Carolina's finest examples of Native American pictographs have survived for 5,000 years.

A well-preserved Ancestral Puebloan ruin tucked beneath a desert cliff.

The longest continuous lava tube in Oregon.

Dig for your own trilobites in this goldmine of invertebrates.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

An extraordinary mixture of natural beauty and man-made phenomena.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

Each year these high desert hills are absolutely covered with poppy flowers in a surreal show of nature.

Where manatees are the snowbird vacationers in these balmy Florida springs.

Take a drunken tour inside the world's largest known geode.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

This "floating island" plateau sits 7,671 feet above the forest floor.

This everlasting lightning storm may be the world's largest generator of ozone.

Thousands of volcanic rocks carved 1,000 years ago.

These overlooked ruins give an intimate look at the Inca Empire's urban planning prowess.

An Inca spa, military outpost or maybe… both?

The sophisticated hydraulic system of the Nazca civilization.

The Incas turned this ancient Wari aqueduct into an imposing defensive gate.

The depictions of slaughter are surprisingly detailed at this mysterious ancient site.

Pre-Incan aqueduct amidst a stone forest in Peru.

An abandoned Incan construction project left behind a mysterious "doorway."