Where any individual building facade (or adjoining facades which abut flush to the same building line) is visible from any public right-of-way or public space (including internal public spaces within a development) and exceeds 80 feet in length, there shall be a clear dimensional differentiation of roofline (i.e., an obvious difference in height) and/or an offset in facade of at least 10 feet, effectively breaking the single facade into two or more facades each no more than 80 feet in length. Where approved by the Board of Supervisors as a conditional use, single facades greater than 80 feet in length may be permitted, where applicant demonstrates to the satisfaction of the Board that the design of the building and its relationship(s) to surrounding buildings and landscaped areas mitigate any negative impacts of long continuous building facade(s) on the character of the RM District. Mitigating factors may include design which emulates characteristic historical building forms which typically included relatively long individual facade lengths such as barns, stables, churches, meeting houses, or other public buildings. Building arrangements which rely on repeated use of the same long facade element shall not be approved.