Stone monuments provided with drill holes to indicate all street lines shall be placed at street intersections and at points of change of alignment, and at the ends of streets should the same not be at a street intersection. The monuments shall be of a suitable hard stone free from ingredients likely to cause disintegration and shall be at least twenty inches in depth five inches wide and five inches long. The monuments shall be set so that their tops will be approximately ten inches below the established grade of the street.
(1955 Code. §1103.20)