One itches to get the one fallen stone upright to re-complete the stability this ancient structure.
Was it covered with an earthen burial mound?
It makes it clear that even in pre-history the region was influential. In later centuries Chinon castle, a couple of miles away, was to rule the Europe of the Plantagenets from Spain to Hadrian's wall in Scotland. Touraine has been the play-park of noble families and kings for a long, long time.
p.s it is now stranded in a field of rape seed; last year it was sunflowers, I think.
see the location on the map of Richelieu locations to the right....