This historic cliffside mansion uses a natural cave for air conditioning.

Patrick Dougherty's fantastic living tree sculptures, mind-blowing but temporary.

In a grove of fast growing walnut trees outside Paris, Illinois, a marker shares the story of a fictional road building culture.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

A collection of outdoor art by renowned muralist Robert Dafford depicts the history of a flooded city.

An enormous natural sandstone bridge in Kentucky.

Symbolic attempt to overcome the issues of life.

Part of a worldwide art project, this mysterious semicircle of concrete shapes holds the pieces of a larger story.

This folk art wall claims to be the world's one and only memorial to the bygone age of hippies.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

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

Like Stonehenge, but with boats and oodles more charm.

In the loving memory of a tragically deceased role-player this Illinois park is decked out with both dungeons and dragons.

The world's largest man-made underground caverns offer unparalleled underwater wonders.

A late sculptor's last project was to turn this abandoned cement factory into a castle-themed amusement park.

An abandoned factory along the Mississippi coated by a giant mural.

A kitschy, creepy St. Louis mainstay.

A floating museum that was sunk by a flood and left to rot in the tides.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

A wax effigy of St. Valentine hides one of the saint's relics.

Speak to a companion on the other side of the room loud and clear through this architectural anomaly.

This spot in St. Louis, marked with a simple sign, has seen more pro baseball than just about anywhere else in the world.

The first rural cemetery west of the Mississippi is home to the elaborate tombs of St. Louis' local beer barons.

An urban forest overtakes what was the greatest failure of utopic urban housing.