The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

What was meant to be a temporary exhibit is now a permanent fixture at the St. Louis Zoo filled with beautiful birds.

This titanic oil company sign is a reminder of the Americana boom of the 1970s and also its commoditization.

A downtown park built on top of unclaimed graves.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

Massive still life just off the highway in Kansas.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

Now nearly abandoned, Kaskaskia was once the capital of Illinois and one of the most important towns on the upper Mississippi.

First known as the "Sample House," this construction mash-up was meant to be a living catalogue of building styles.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

Quirky water tower advertises the long-gone Brooks Tomato Products Co.

Buy a token from the liquor store and you can make this beast spew flames on command.

The only surviving prototype for Buckminster Fuller's house of the future.

The only presidential monument to display a late POTUS's actual casket.

Symbolic attempt to overcome the issues of life.

Giant granite rocks standing end-to-end like a train of circus elephants.

In the St. Francois Mountains in the Ozarks at 1,772 feet above sea level, Taum Sauk Mountain is the highest (and possibly oldest) peak in Missouri.

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

Erosion and time have created a naturally-formed water park.

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

The park that the Chicago Stockyards built.