The famous stone circle at Stonehenge. Photo courtesy of Ludwig Boltzmann Institute for Archaeological Prospection

A motorized magnetometer is used to survey the Stonehenge site. Photo courtesy of Ludwig Boltzmann Institute for Archaeological Prospection

Using survey data that shows post-hole structures that once contained wooden posts, an artist created this 3D visualization of the internal structure of a mortuary building. Photo courtesy of Ludwig Boltzmann Institute for Archaeological Prospection

Another artist's visualization of the long barrow mortuary building just before it was covered by material excavated from ditches dug along the long sides of the structure. Photo courtesy of Ludwig Boltzmann Institute for Archaeological Prospection

A motorized ground penetrating antenna array surveys the site Stonehenge. Photo courtesy of Ludwig Boltzmann Institute for Archaeological Prospection

Magnetic data images show the 19 newly discovered monuments beneath the Earth around Stonehenge. Photo courtesy of Ludwig Boltzmann Institute for Archaeological Prospection

A prehistoric ring ditch at Stonehenge shows up as a Smiley Face in this magnetic data image recorded during the Stonehenge Hidden Landscapes Project.