The Georgia collection is available online from two sources: Sanborn Fire Insurance Maps, 1884-1922 (Free) and Digital Sanborn Maps, 1867-1970 (ProQuest subscription required).
Navigating the images is made easy by an "index" map. When viewing a city's index map, you can click on a part of that map to view a particular section of the city. You can navigate from section to section, exploring streets and buildings. Streets will include address numbers and buildings may include information about the business, building materials, number of floors and any other information that might be of importance to firemen. Make sure to check out the map's Key, Seal and Index page for more information.
For example, see: Elberton, GA in 1885 and 1922. In 1885, according to the seal there was a population of 1,000, no Steam or Hand Engines and water facilities were "not good." By 1922 there was a population of 7,000 with 4 firemen on duty at all times and a detailed description of a complex water system. This can be very valuable information for understanding where our ancestor came from.