“Historic preservation district (HPD)” means a concentration, linkage, or continuity of sites, buildings, structures, or objects united by architecture or historical plan, physical development, or theme. There are two types of HPDs: geographic and thematic. (Also see “geographic historic preservation district” and “thematic historic preservation district.”) (Also see the City’s HPP Section 3.0, Historical Resources – Historic Preservation Districts.) (Ord. 3196 § 3, 2011).