The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

This erect, phallic geological spire wasn't always named so domestically.

The first declared National Monument in the United States.

A cemetery housing wild west legends in South Dakota.

An experimental, automotive replica of Stonehenge.

The ruins of the northernmost pueblo in the Americas tell the story of a mixing of native cultures.

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.