The Harvard Map Collection contains one of the world’s finest collections of maps. Although their atlases are in HOLLIS, many of their individual maps are not. Som a visit is useful. As well as political and topographic maps, they have numerous thematic maps which map demographic, social, and economic other features.
Atlascope offers overlays of historic maps onto modern map of Boston and immediate suburbs.
CartoMundi is an international collective catalogue offering about 35 000 citations for cartographic documents held in about 20 map libraries. Also includes over 2500 digital reproductions representing Europe and Mediterranean countries.
Histoire de la cartographie Bibliothèque Nationale de France exhibit
Barry Lawrence Ruderman Antique Maps (commercial site with well-annotated images)