Cheater! When you construct stonewalls in New England you do it without and adhesive or concrete to hold the rocks together. The post of rocks here looks to be held up by some cement. Even the best of wall builders would have a task upon their hands if they tried to keep these round rocks at the crown from rolling about. We've got a few stonewalls running about up back on property. Not pretty. Just boulders stacked upon boulders. Nothing fancy, but it gets the job done.