California Code, Public Resources Code - PRC § 5019.59

Historical units, to be named appropriately and individually, consist of nonmarine areas established primarily to preserve objects of historical, archaeological, and scientific interest, and archaeological sites and places commemorating important persons or historic events.  The areas should be of sufficient size, where possible, to encompass a significant proportion of the landscape associated with the historical objects.  The only facilities that may be provided are those required for the safety, comfort, and enjoyment of the visitors, such as access, parking, water, sanitation, interpretation, and picnicking.  Upon approval by the commission, lands outside the primary historic zone may be selected or acquired, developed, or operated to provide camping facilities within appropriate historical units.  Upon approval by the State Park and Recreation Commission, an area outside the primary historic zone may be designated as a recreation zone to provide limited recreational opportunities that will supplement the public's enjoyment of the unit.  Certain agricultural, mercantile, or other commercial activities may be permitted if those activities are a part of the history of the individual unit and any developments retain or restore historical authenticity.  Historical units shall be named to perpetuate the primary historical theme of the individual units.