In interesting resource is this 50s map of downtown Los Angeles showing many theatre locations.
Click on the map for a larger view. It's from Tom Wetzel's
wonderful "Uncanny" website. The map appears on a page
devoted to a tour of the Subway Terminal area.
The map now appears on a new Theatre Maps page that's part of the Downtown Theatres website. What's on there now is just the beginning of what will be a growing collection.