Ground plans are inadequate. The structure is studied in three dimensions. However, plans are useful. None exist of Trethevy Quoit so we have made our own. We have also taken the liberty of numbering the stones in a logical manner which leaves room for adjustment. You will have to be more specific, please regarding the capstone. What exactly do you want to know?
Something is not right. This message is just to keep things from messing up down the road