The RKO Hillstreet
Michelle Gerdes, of the Los Angeles Historic Theatre Foundation, has been spending days rummaging through the Library's treasures and, among other adventures, taking photos of these maps.
You can click on it for a larger view -- note that the auditorium is set on the lot at a slight diagonal.
Another look at the building, this time via a detail from a 1948 L.A. Examiner aerial photo from the USC Archives. Notice here that the garage building shown behind the stagehouse has been demolished.
Check out our web page on the RKO Hillstreet for more on the theatre.