means any cloth, card, paper, metal, glass, wooden, plastic, plaster or stone sign or other sign, device or structure of any character whatsoever, including a statuary or place for outdoor advertising purposes on the ground or any tree, wall, bush, rock, post, fence, building or structure. The term "placed" shall include erecting, constructing, posting, painting, printing, tacking, mailing, gluing, sticking, carving, or otherwise fastening, affixing or making visible in any manner whatsoever. The area of an advertising structure shall be determined as the area of the largest cross-section of such structure. Directional, warning, or any other signs posted by public officials in the course of their public duties shall not be construed as advertising signs for the purpose of this ordinance.