It shall be unlawful for any person to block or obstruct the use of any street or alley, including sidewalk areas, or the free use thereof, without first obtaining permission from the manager. The foregoing prohibition does not apply to any marquee extending from a building over any sidewalk; providing, however, that no marquee shall extend closer than two feet from a line drawn vertically from the outside of any curbing or curb line provided for in this title.