Cal. PRC § 5031

“Qualified historical property” means privately owned property which is not exempt from property taxation, is visually accessible to the public, and which is:

(a) All landmark registrations up to and including Register No. 769, which were approved without the benefit of criteria, shall be approved only if the landmark site conforms to the existing criteria as determined by the California Historical Landmarks Advisory Committee or as to approvals on or after January 1, 1975, by the State Historical Resources Commission. Any other registered California historical landmark under Article 2 (commencing with Section 5020) of this chapter, except points of historical interest, and which satisfies any of the following requirements:

(1) The property is the first, last, only, or most significant historical property of its type in the region;

(2) The property is associated with an individual or group having a profound influence on the history of California; or

(3) The property is a prototype of, or an outstanding example of, a period, style, architectural movement, or construction, or if it is one of the more notable works, or the best surviving work, in a region of a pioneer architect, designer, or master builder; or

(b) A property which is listed on the national register described in Section 470A of Title 16 of the United States Code; or

(c) A property which is listed on a city or county register or inventory of historical or architecturally significant sites, places or landmarks, provided, that such property satisfies any of the requirements set forth in paragraph 1, 2 or 3 under subdivision (a).