A century-old network of freight tunnels underneath the city's historic business district.

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

This museum celebrating the almighty dollar lets visitors literally stand in the shadow of a million bucks.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

The 30,000-volume library is one of the world's most impressive poetry collections.

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

A goddess-topped water fountain in Chicago was created thanks to the dreams of a thirsty newsboy.

The final resting place of up to 6,000 Confederate soldiers, the largest mass grave in the Western Hemisphere.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

An avant garde art museum at the University of Chicago.

All of Chicago's wood-paved streets are long gone but two alleys remain.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

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

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

A gregarious Ohio resident has been building his whimsical temple to peace for decades.

Turnip-shaped island just off the Michigan shore in Lake Huron.

This museum remembers an apocalyptic cult that became more famous for baseball than religious radicalism.

A rural hall of justice holds the world's only comic book and superhero museum.

These sprawling mines once served as a source of plaster and today serve as a storage facility.

The origin of the Nixon tapes is rooted in technological incompetence as much as secrecy.

At Fountain and Division, in the shadow of Kendall College of Art and Design, lays the story of a fictional culture whose political system was used under license and who finally rebelled.

There is an art, a science, and certainly a responsibility to occupying The Big Red Chair, and this is where it's learned.

A singular collection of hand-built art deco cars are held in a building with style to match.