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

Mounds, rune stones, and a 1,000-year-old church, left behind by Denmark's first two kings.

Four alabaster giants contemplate the tides on the shore of Denmark.

The largest earthwork effigy in the world.

A real flying saucer, contracted by the U.S. Air Force.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

An abandoned asylum incorporated into a college campus.

This whimsical campus lawn is dotted with large sculpted numbers and hidden mathematical formulas.

The inventor of a number of hybrid corn species is immortalized with a field of giant corn.