Together they left this world, and together they shall remain for all eternity.

Often referred to as the largest spring in America.

The largest riverfront opening cave in the Ozarks.

An underground river pushes more than 200 million gallons out of this Missouri spring every day.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

The oldest bar in Missouri is hidden within a limestone brewery cellar more than 50 feet underground.

A beloved, quirky little fountain featuring a large frog spitting water at a naked boy.

The ruins of a 19th century shelter run by the Independent Order of Odd Fellows.

This abandoned prison castle has become an imposing gallery of graffiti art.

Soak in the soul of Kansas City at the oldest continually-operating jazz club in the country.

An abandoned concrete jungle surrounded by a lush park.

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

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

A geological oddity formed by two rivers carving out a mass of limestone on both sides.

Like Stonehenge, but with boats and oodles more charm.

This majestic tree has survived 400 years of storms, droughts, and floods, and is a beloved natural landmark in Missouri.

A kitschy, creepy St. Louis mainstay.

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

Step into Monet's world at this fine-dining restaurant in the middle of a New Jersey sculpture park.

A mysterious light floating in the trees of Arkansas may be a piezoelectric effect.

Twenty-year effort to raise a castle using tools and techniques from the 13th century is now abandoned in the Arkansas woods.

If there's another drive-through golf-cart bar in a bat-filled cave on top of a mountain, we don't know about it.