For historians of Los Angeles, and librarians such as LAPL maps Glen Creason, old reference tools called the Sanborn Fire Insurance atlases are invaluable. They can show a researcher what was on the ground in a specific place in, say, 1901. Seeing the layout of buildings and the functions described by insurance inspectors at the time can offer a lot of clues to the past. Creason writes at the Huffington Post:
While Fire Insurance atlases were originally created to determine risk in buildings being considered by insurers as far back as the mid-nineteenth century, they now offer layers of fascinating information about cities across America. The serendipity of wandering off on intellectual tangents once brought on by thumbing through a card catalog file has now gone digital and it is a lot easier on the back in some cases. Atlases such as the Sanborns, Baist or Dakin are indispensable in tracing the growth of Los Angeles from some adobes by the river to the megalopolis of today. While there is no substitute for spreading atlas pages or flat maps beneath your magnifying glass on a flat surface, the next best thing is an online archive with good software.
More over there.
Above is a 1929 Sanborn page of the old Metro-Goldwyn-Mayer studio in Culver City, which lay south of Washington Boulevard and west of Ince Way. Click to enlarge. Below is a page showing the 1906 layout of LA's famous Chutes Park, an amusement part on West Washington Boulevard where the early Los Angeles Angels played.