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

The first declared National Monument in the United States.

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

The highest point in South Dakota contains the ashes of Valentine McGillycuudy, the "Holy White Man."

One of America's first dinosaur parks gives a window into Depression-era paleontology.

This replica stave church looks like a piece of Norway was simply plopped down in South Dakota.

The crumbling structure is a rare surviving relic of the area's bygone mining industry.

An antique Beechcraft airplane serves as a giant windsock for people driving through the blustery open country of eastern Wyoming.

This shallow pit was once used to send over 20,000 buffalo plummeting to their death.

Yes, this monument is aware that it is about 20 miles away from the actual center of the United States.

A cemetery housing wild west legends in South Dakota.

A striking sculpture built to honor the women of the Lakota and Dakota Nations.

A museum, walk-through diorama, and library nestled under one castle-like roof.

A fitting attraction for the corn capital of the world.

A roadside collection of over-sized iron creations that are a bit more macabre than most.