Ever since Wittkower published Architectural Principles in the Age of Humanism in 1949, in which he showed that Palladio's villa plans are based on a tartan grid, it seemed that Palladio's design principles had been encapsulated. When subsequently, in 1978, Mitchell and Stiny enunciated all the topological possibilities for Palladian villa plans, it appeared that the case was closed. Freedman and Hersey have since shown that it is precisely in the application of specific building dimensions and proportions that additional design rules come into play, however. The present study builds on the work of Freedman and Hersey. It uses and extends their method which involves incorporation of the known design principles for Palladian villas, as given implicitly in Palladio's Four Books of Architecture and in his built works, into a computer program capable of generating schematic plans and elevations based on those principles and visually comparing the generated plans and elevations with the known works of Palladio. In cases of disagreement, the reasons for the disagreement help formulate further design rules.