All signs, awnings, and canopies extending over any public sidewalk, street, avenue or other public place must be securely fastened and constructed so that there will be no danger of being dislodged by ordinary winds or falling from any other cause. No sign or canopy shall be erected or maintained extending over any public sidewalk, street, alley, or other public place in such a location as to obstruct the view of any traffic light or signal or to obstruct the view of motor vehicles.