This cathedral dedicated to Louis IX, sainted King of France, holds many secrets.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

Tour the luxe "glass cage" that inspired and unnerved the architecture world upon its debut.

Behind a modern brick exterior lies the oldest continuously-operating lunch-car diner in the United States.

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

Its eclectic exhibits range from the world’s first motorcycle to Luke Skywalker’s Land Speeder.

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

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

This cemetery is all that remains of a school for "wayward" girls.

What was once the second largest steel mill in the US is now a sprawling complex of modern ruins.

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

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

This sprawling mini-golf empire is an impressive testament to a disappearing attraction.

Urban explorers embraced America's now demolished first suburban mall, south of Chicago.

A small abandoned and abused cemetery that has become a magnet for ghost hunters.

This overgrown Illinois water park offers a whole new type of adventure.

A historic beacon built in the aftermath of the worst maritime disaster on the Great Lakes.

This morbid, delightful curiosity shop offers everything from animal bones to human teeth.

An antiquated German apothecary on Chicago's North Side.

A century-old hotspot for jazz, frequented by everyone from Charlie Chaplin to Al Capone.

A hollow cement depiction of time's inexorable effect on the human body.

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

A haunting statue called "Eternal Silence" has quite the reputation among visitors with active imaginations.

Former meatpacking facility turned vertical farm and sustainable business complex.