Category A or historic resource properties include buildings listed in or formally determined eligible for listing in the California Register of Historical Resources, or listed in an adopted local historic register. The term “local historic register” or “local register of historical resources” means a list of resources that are officially designated or recognized as historically significant by a local government pursuant to resolution or ordinance.
The buildings under this category have to follow very strict design guidelines from the Secretary of the Interior's Standards for the treatment of historic properties as soon as commencing any alteration. Owner would have to take into consideration the design limitations of the facade and interiors which may also determine additional costs due to preservation process of it's features.
CityStructure Reports will show you under which historical category designation your property may fall.