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

The world's longest known cave system.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

A chilling disappearance (and rescue) of a child uncovers a geological mystery.

The farm where one of America's greatest leaders was raised is now a well-appointed landmark.

The site of a 19th century "dream city" that almost rivaled Chicago before being swallowed by the Indiana sand dunes.

You have to love a museum with a truly dedicated focus. A focus on Superman, for example.

This historic hotel invented the chocolate brownie.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

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

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

One of the oldest living oak trees in the Southeast.

This recently rediscovered Civil War-era submarine was the first to ever sink an enemy ship.

Paths are maintained, but trees have taken over plots.

South Carolina's last remaining slavery auction house is now a museum devoted to its own tragic history.

There aren't too many operational funiculars around, but Pittsburgh has two!

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

A river with some unusual, and occasionally dangerous, habits.

Known as the "Cross At The Crossroads," this massive metal cross is just short enough to avoid the FAA.

A science teacher's dream.

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

The palatial McDonald's that inspired Wesley Willis.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.