A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

A beautiful geyser under environmental threat.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

Examine the impact of the horse on Great Plains culture through exhibits on ranching, rodeo, and the Native American way of life.

A notoriously corrupt Chief of Police's deteriorating Greek-themed playhouse.

A fitting attraction for the corn capital of the world.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

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.

An Iowa town celebrates its heritage with the tallest working Dutch windmill in North America.

The only museum in the world dedicated to the history of sprint car racing, next to one of the country's most historic dirt tracks.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

This rare vessel mixed luxury with labor before being converted to a museum and sometimes haunted maze.

The watery grave of an impractical idea.

Every winter, dozens of otherworldly ice structures sprout up from a rigged up artesian well.