This text contains some ideas presented in the final paper of the Master Degree in History Theory and Critics of the Architecture School at the Federal University of Rio Grande do Sul - Porto Alegre, 2003, oriented by the Arc. PhD. Douglas Vieira de Aguiar. The initial proposition was to verify whether there is or not, a specific urban model to colonial cities in Iberoamerica. It is assumed that the fundamental value of these experiences resides in the capability of selection, synthesis and application of principles of a millenary urban tradition. To validate this hypothesis, 21 Hispanoamerican and Lusobrazilian towns have been analyzed through the observation of preserved historical cartography, the systematization of these maps and their classification according to a proposition of urban grids categories.