This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Elevated freight railway turned wildly successful urban park.

Largest tulip festival in America, includes fireworks, a parade, and a carnival.

The body of one of the world's most famous outlaws is covered in cement and iron to prevent it from being stolen.

Home to the world's largest refracting telescope and the birthplace of modern astrophysics.

A unique botanical garden housed in three giant geodesic domes.

Wisconsin's most celebrated export gets the royal treatment on I-94.

A 19th-century horse lover's bequest led to the construction of this unique fountain in Chicago.

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

This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

A historic and oft-filmed prison stands in a Chicago suburb.

An actual 1957 Cadillac De Ville, encased in 15 cubic yards of concrete.

A onetime gangsters' hideaway where you can dine on steaks, fine wines, and cigars just like they once did.

The palatial McDonald's that inspired Wesley Willis.

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

A source of civic pride, though the reason for its construction is unknown.

The sign to a demolished amusement park now stands in front of a local library.

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

This national park dedicated to the tallgrass prairie ecosystem still displays its military past.

An exhibit of items from the mental institution where Mary Todd Lincoln lived after her son conspired to have her committed.

This house renovated by Frank Lloyd Wright was the centerpiece of a lavish 20th-century estate.

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

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