The villas of Andrea Palladio have been among the most influential buildings in history. Drawing on the architect’s original published legacy of forty-odd designs, George Hersey and Richard Freedman reveal the rigorous geometric rules by which Palladio conceived these structures. Where most earlier attempts to analyze the villas are mere lists of numbers and ratios that ignore space distribution, the present rules produce actual designs. Using a computer, the authors test each rule in every possible application, establishing a degree of validity not possible in ad hoc analyses. Progressing from the architect’s most obvious to his subtlest ideas, the computer ultimately creates villa plans and facades that are stylistically indistinguishable from those of Palladio himself. Possible Palladian Villas opens the way to similar analyses of other such “paradigmatic” designs, whether Chinese screens, Greek temples, baroque churches, or Frank Lloyd Wright’s Prairie Houses. In fact a new approach to architectural history emerges: we can study designs that a given master might have produced but did not. Palladio’s actual buildings, along with those of his generations of imitators, are set into the context not only of a new theory but of a new type of theory. Along with the Macintosh disk that runs the program, Possible Palladian Villas will fascinate the design community and students of architectural style, symmetry, and geometry. It will fill architectural historians with bracing dismay.