DR. CURTISS HOFFMAN, author of "Stone Prayers: Native American Stone Constructions of the Eastern Seaboard," and STEVE DiMARZO, a specialist in New England's antiquities, join us to discuss the diversity of stone monuments from Georgia to southern Canada, with a special emphasis on New England. We know there were cairns, platforms , balanced rocks; but what were their functions? What role did their positioning near streams play? They also examine their constructions at different elevations. But more importantly, who were the engineers? Let's get to know them.