The problem with attempting to find auitable map images n the web for vairous games is that it's very difficult to find a map that has the same "look and feel" as the rest of the game.

Many resources on the web. One of the best (for none-copyright old/antique maps is -
http://www.ihrinfo.ac.uk/maps/webimages.html#amergen

Ok, many of the maps are quite simple but there is SO MUCH on this site I'm pretty sure you canfind something vaugely suitable.

Another option is to use a map from another, similar, game.