If an individual building has enough prominence to have had an entire book written about it, then you can search the name of the building as a subject, e.g.: Schindler House (Los Angeles, Calif.) in the UCLA Library Catalog. If not, search a subject such as a building type, subdivided by California and the name of the city where the building is located, or subdivided by California, Southern.
Relevant subject headings:
Architecture and climate--California.
Architecture and energy conservation--California.
Architecture, Domestic--California, Southern.
Architecture, Domestic--California--Los Angeles.
Architecture--California, Southern--History--20th century.
Architecture--California, Southern.
Architecture--California--Los Angeles.
Architecture--California--Palm Springs.
Architecture--California--Pasadena.
Architecture--California--San Diego.
Architecture--California--Santa Barbara.
Architecture--Study and teaching--California.
Art deco (Architecture) - California.
Church architecture--California--Los Angeles.
Eclecticism in architecture California.
Hillside architecture--California.
Interior architecture--California.
Interior decoration--California.
International style (Architecture)--California, Southern--Case studies.
Landscape architecture--California, Southern.
Library architecture--California.
Modern movement (Architecture)--California.
Regionalism in architecture--California, Southern.
Theater architecture--California.
Vernacular architecture--California.