Various structural elements have construction methods and potential problems that deserve attention. Points of note include: the ‘ratchet effect’ on rubble-filled walls of repeated freezing and thawing; the possibility of mortar shrinkage or of stone decay through excessive stress; the crucial role of crossing piers which carry a tower, and how they can be strengthened (as at Milan and Worcester); the (maybe counterintuitive) structural contribution of pinnacles; the detailed actions of flying buttresses, and how they may fail (as at Amiens) if they are not ‘flat arches’; the importance of binding ribs to walls by single ‘through-stones’; how stone windows handle thrusts from the wall above and wind outside, starting with rectangular windows and moving on to rose windows; and the actions in response to live and dead loads on cantilevered stone stairs, whether piecewise straight with corner landings or geometrical (as in a round tower). Calculations about structural actions (of flying buttresses, stone windows and stone stairs) can be based on simple statics.