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.

The first declared National Monument in the United States.

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

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

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

The palatial McDonald's that inspired Wesley Willis.

What was once one of the country's largest confectionary plants is now an abandoned ruin, but is still pretty sweet.

A display of magnificent stained glass windows is the first exhibit of its kind.

A spectacular remnant of an Adler and Sullivan masterpiece that was destroyed in 1972.

Odd, decrepit fountain honors Chicago author who had mixed feelings about his hometown.

Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.

Partially submerged Buddha heads freckle Chicago’s neighborhoods.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

No one knows how many bodies are in this vault in a Chicago public park.

Not to be confused with the iconic New York City skyscraper, this Chicago building is a vibrant hub for artists.

Once called the "Polish Gold Coast" it is an icon of the neighborhood that bears its same name.

To find the "unicorns of the deep" you've got to go downstairs.

This historic-shipwreck-cum-diving-spot can still be seen poking its boiler out of the Lake Michigan waters that claimed it.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

This modest post office sits on the site of H.H. Holmes' famous murder castle.

A hot dog stand where the heads are just as hot as the dogs.

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.