Old Maps Online Repository of historic maps from collections around the world.
Perry-Castañeda Library Map Collection Online map collection covering the world, countries, states, cities, etc. from the University of Texas at Austin. Includes historic and modern maps. Includes color version of Sanborn Fire Insurance maps and its key to the colors and abbreviations.
Sanborn Fire Insurance Maps A Subscription database of the Sanborn Maps held in the collections of the Geography and Map Division at the Library of Congress. Over 6,000 of the sheets are available digitally. Free version, in color, at the University of Texas, Texas Sanborn maps