At another site (probably Avebury, but I don’t know) a gubmint project to raise all the fallen stones led to the discovery of the remains of a 15th or 16th c man (dated based on the coins found in a pocket) who apparently had been involved in the use of the site as a quarry, and paid the price.
It describes 640 prehistoric sites throughout England -- there are many more in Scotland and Ireland. Of Avebury's original 98 standing stones only 27 remain today (unless erosion has toppled more since the book was written). I walked the 1,280 meter circumference of Avebury's Great Ditch and was astounded by the sheer volume of dirt and chalk that were removed with nothing more than bone tools.