The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

The world's longest known cave system.

One of the largest collections of merchandise from the famous British sci-fi show can be found smack in the middle of Indiana.

A collection of over 2000 air-moving devices of all kinds displayed in the Fanimation headquarters.

Nature and art meet in this curvy creation

This elaborate estate contains a stunning marble aviary, a sunken conservatory, and a magnificent music room with a two-story pipe organ.

This mysterious hill seems to pull objects uphill.

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

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

The longest navigable underground river in the United States is home to countless blind and albino animals.

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

400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

European castle ruins in an American state park are actually the product of death and grief.

When you can afford only half a road, you build only half a road.

This museum located in the "Corn Cob Pipe Capital of the World," chronicles the history of cob pipe.

A mysterious light of unknown origin on the backroads of Missouri.

This otherworldly church spire reaches up toward the heavens.

A cave 150 feet beneath Kansas City is the perfect climate for growing 10,000 delicate orchids.

This wooded grove of beautiful hand-built stone grottos is a hidden gem within a shuttered Franciscan monastery.

The world's second largest rocking chair is found on Route 66 in Cuba... Missouri.

The maximum security facility was once thought to have "the bloodiest 47 acres in America."

This museum presents a dogged pursuit of 500 years of veterinary history.

A perfect circle of twenty-four mysterious holes dates back to prehistoric time.