In the Second Century A.D. Claudius Ptolemy was the librarian at Alexandria, the greatest center of learning in the Classical world. Ptolemy wrote two major works, the Almagest, an account of the heavens, and the Geographia, the first atlas of the world. This latter consisted of Ptolemy’s compilation of all known geographic information, including instructions for how to make maps. Rediscovered in the middle ages, the Geographia had a profound impact on the awaking western European mind. Ptolemy opened to view large parts of the unknown world to an audience just starting to explore beyond its narrow horizons. His structure for making maps, with longitude and latitude, and his usual northern orientation for the maps, became the standard from then right up to the present. Such was the impact of Ptolemy’s work that even in the sixteenth century, a millennium and a half after it was produced, when Ptolemy’s geographic conceptions were known to be wrong, maps based on these conceptions were issued time and again. This map comes from a sixteenth century edition of the Geographia issued by Sebastian Munster.