New imaging technology has both confirmed and corrected an old eighteen-forties map of the Junction Earthworks. The earthworks were first mapped in the eighteen-forties by Ephriam Squire and Edwin Davis and included in their book, Ancient Monuments of the Mississippi Valley, the first publication of the Smithsonian Institution. The enclosures were visible on the landscape then, but by the mid-nineteen hundreds they had been leveled by farming, the fate of many earthworks across the region. New magnetometry data show that Squire and Davis had missed the details of the Quatrefoil and recorded the small squircle as a circle, but most of their errors were quite minor. Magnet and other remote sensing technologies allow archaeologists to reveal the remains of earthworks and other ancient features that were never before recorded. The striking new magnetometry image of Junction helped persuade donors from across the region to save the site from development and turn it into the park enjoyed today.