A lot is being made of the "hole"...one poster, in the other thread alluded to it being for the erection of a maypole(yes I know it was a tongue in cheek remark)...but it might not be that far off the mark....perhaps(and only perhaps) the hole was used as an aid to building....by inserting a sturdy lever-style piece of wood(this could explain what was described as a "squircle" too as this would give a good grip of a piece of timber) for aiding in raising the slab and moving it into and holding it in position until the wall structure was fully stabilised...has anyone considered a simplistic theory??