The City Engineer shall find and mark the lines of all streets, alleys and public grounds and any person who is about to erect a building, install a curb or pave any sidewalk shall have the Engineer ascertain and mark the street or curb line, as the case may be, and the grade, if one has been established. No person shall erect any building or fence thereon in violation of any of the provisions of this chapter. (1947 Code, Sec. 6-55.)