The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

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

This supper-club-turned-concert-venue still serves drinks at its original rotating bar.

L. Frank Baum wrote part of the "Wizard of Oz" series in this wooden Victorian beach resort.

More than 5,000 contemporary and "historic" mustards from around the world.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

This monolithic statue was erected in honor of Chief Black Hawk (even if it wasn't made to look like him).

A bizarre house filled with an astounding array of collections.

The city of Rockford, Illinois is symbolically protected by a quartet of fittingly stony sentinels.

The palatial McDonald's that inspired Wesley Willis.

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

This awkward aquarium sculpture is one of the strangest statues in Chicago.

Once at the center of U.S. finance, the historic Trading Room was meticulously recreated piece by piece and rebuilt in the Art Institute.

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

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

A beloved Chicago music venue offering cold beer and lots of “Friendly."

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

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

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

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

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

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.

This historic hotel invented the chocolate brownie.

What's left of the ruins of the 1893 Columbian Exhibition, or World's Fair, also known as the White City.