Wis. Stat. § 167.20: Stairway guards.

(1) The owner of any building or other structure which has an open stairway or area way leading to or abutting upon any sidewalk, and the owner of any real estate adjacent to or abutting upon any sidewalk and which is lower than such sidewalk, shall sufficiently guard such stairway or area way or property as to prevent accidents.

(2) Any person who violates this section shall be fined not less than $25 nor more than $100 or imprisoned for not less than 30 days nor more than 6 months. Each day during which a violation of this section continues shall be considered a separate offense.