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.

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

This vintage train once gave new meaning to “swimming upstream.”

This geodesic gallery holds a collection of painted spheres that make traditional canvases look lazy by comparison.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

Dedicated to the history of the 1,000 nuclear missiles that once covered the Great Plains.

One of the first intercontinental ballistic missile sites in the United States.

A ghost town now swarming with dozens of prairie dogs.

These former Cold War launch sites have been preserved for tourists to see where the button might have been pushed.

On the windswept Dakota plains there is a memorial to circus workers who were struck down by lightning.

A town honors its legacy of traditional American Indian pipe carving with one gigantic pipe.

Known as "The Hill of the Little Devils."

This once prosperous community was home to European settlers and the Ojibwe.

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

Abandoned businesses, homes, and rusted cars are all that remains of this stopover town.

The remnants of an early American attempt at missile defense.

The deserted railroad town had a last gasp as a ghost town attraction before being abandoned for good.

America's smallest town is run by its single citizen/mayor/librarian/bartender.