Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

This 50-foot rock formation looked like a face that was once believed to be that of a Native American chief.

A coastal rock outcrop with mysterious inscriptions variously attributed to Native Americans, Portuguese, Phoenicians, Norse, and more.

Some North Carolina Cherokee have been keeping their history alive for decades with a single play.

A set of ancient drawings in the desert of Peru that are so massive, many of them can only be fully seen from the sky.

Mysterious ancient boulder carved with petroglyphs in the mountains of Western North Carolina.

Ancient human, animal, and geometric figures drawn in the earth.

America's oldest archaeological site or a muddled case of wishful thinking.

A perfect circle of twenty-four mysterious holes dates back to prehistoric time.

One man's quest to fix his toilet unearthed over 5,000 artifacts spanning more than 2,000 years of history.

Over fifty whirling pools left by the glacial age.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

A petroglyph map of the upper Snake River carved by prehistoric hunter-gatherers.

Hundreds of drawings left by the land's previous inhabitants remain mysterious.

See massive fossils that are over 200 million years old in northeastern Arizona.

A working cattle ranch with remarkably well-preserved prehistoric petroglyphs and ancient ruins.

These ancient ritual mounds are our best window into the culture of the ancient Mississippians.

A mysterious collection of stones stand outside a small New England town.

This famous city eluded concrete detection until the early 2000's.

The largest stone circle in the world has ended up bringing up more questions than it has answered.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

Possibly the oldest of Britain's ancient henges is also one of its most stark.

The discovery of this Neolithic settlement, which contained a Stone Age "cathedral," threw archaeologists for a loop.

Enter the world under the hill at this ancient UK burial chamber.