Permanent concrete monuments shall be accurately set and established at the intersections of all outside boundary lines of the subdivision; at the intersections of those boundary lines with all street lines; at the beginning and end of all curves; at points on curves where the radius or direction changes; and at such other points as necessary to establish definitely all lines of the plat. Stone or concrete monuments shall be at least thirty-six inches long and at least six inches in diameter, and shall be provided with an appropriate center point. Solid iron pins five-eighths of an inch by thirty inches or iron pipe monuments at least one inch in diameter and at least thirty inches long may be used at all other points including lot corners.