It shall be unlawful for any person, firm, corporation, common carrier or governmental agency to erect, paint, alter, locate or relocate; reconstruct or change in any manner by rewording or otherwise; or maintain or cause to be erected, painted, located or relocated, reconstructed or changed in any manner by rewording or otherwise, or maintain any sign or sign structure without first having obtained and paid for, and having in force or effect, a permit from the Construction Official. Every sign for which a permit has been issued pursuant to this chapter shall show the permit number thereon.