The Library of Congress Geography and Map Division has scanned their enormous collection of fire insurance maps published by the Sanborn Map Company. Every state of the United State is included plus the District of Columbia.
This site contains 4,445 maps by the Sanborn Map Company depicting commercial, industrial, and residential areas for 133 Georgia municipalities. Large zoomable images.
Do not miss also the broader collection using the topic "Real Property" which includes other large scale mapping of the state of New York. This is a growing collection.
The holdings range in date from the 1880s to the 1950s and cover more than 150 cities and towns across the state. North Carolina Maps features online all of the North Carolina Collection's Sanborn® maps produced through 1922.