DOQQ

http://www.crwr.utexas.edu/gis/gishydro00/Class/trmproj/Donnelly/termproject.htm

A DOQQ map is  an aerial picture that is geometrically correct.  The scale is correct and you can use the  map to measure distance.  in this map the scale is correct and would be a good map to use to see how far something's true distance is.