This hidden stream beneath Indianapolis makes an appearance in the best-selling novel "Underground Airlines."

One of Chicago's last seafood smokehouses perfects a dying breed of fishcraft.

This library and museum is dedicated to the life and literature of the Indianapolis native author.

A hidden network of subterranean passageways lies tangled beneath Indianapolis' bustling City Market.

A 30-year-old Sycamore tree grown from a seed taken to the moon and back.

This Indianapolis landmark offers a secret panoramic view of the city. 

At the top of the hour, this steam-powered clock's eight brass whistles play "Back Home Again in Indiana."

Limestone caves with spectacular showcase chambers.

Hidden on a cattle ranch in Arizona, this bookstore has been celebrating Southwest literature for more than 40 years.

This small memorial is dedicated to the Perryville State Prison firefighters who perished fighting the Dude Fire in 1990.

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

A once popular resort—said to be the vacation spot of gangster Al Capone—now remains abandoned in the woods of Arizona.

A partial tunnel blasted into a steep ridge is all that remains of a failed railway across Arizona.

A stealthy Apache hideaway that became the haunting site of a mass grave.

The large rock formation where the Shawnee prophet Tenskwatawa stood and encouraged his warriors during the Battle of Tippecanoe.

Hidden beneath a bridge, this waterfall is known for the large amounts of graffiti painted on its base.

In the remote high desert of New Mexico, a strange array of poles beckon fury from above.

A self-built castle made by a mysterious man.

A mysterious "wedding cake" castle in the middle of the urban desert.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

Colorado's only true geyser is hidden within the San Juan National Forest.