The maps drawn brefore the arrival of Hernan Cortes in the Valley of Mexico testify to the characteristics of Mexico City and its surroundings in ancient times. Before the 19th century, geographers and topographers outlined maps by just looking at the terrain on inspection tours. These documents, now obsolete, are sketches and some are truly works of art. After this period, cartography advanced thanks to the development of geodesy and astronomy, achieving thus authentic geographic charts. To admire these documents in museums, societies, universities and historical archives is today a most pleasant and fantastic experience.