The world's most artful and skillful stone architecture is found at Tiahuanaco at the southern end of Lake Titicaca in Bolivia. The precision of the stone masonry rivals that of the Incas to the point that writers from Spanish chroniclers of the sixteenth century to twentieth-century authors have claimed that Tiahuanaco not only served as a model for Inca architecture and stone masonry, but that the Incas even imported stonemasons from the Titicaca Basin to construct their buildings. Experiments aimed at replicating the astounding feats of the Tiahuanaco stonecutters--perfectly planar surfaces, perfect exterior and interior right angles, and precision to within 1 mm--throw light on the stonemasons' skill and knowledge, especially of geometry and mathematics. Detailed analyses of building stones yield insights into the architecture of Tiahuanaco, including its appearance, rules of composition, canons, and production, filling a significant gap in the understanding of Tiahuanaco's material culture. "Jean Pierre Protzen and Stella Nair have produced one of the best treaties on the architecture of Tiwanaku" -- José M. Capriles, Latin American Antiquity "En resumidascuentas, un libro fascinante desde cualquier punto de vista." --- reporterodelahistoria.com Detailed analyses of building stones yield insights into the architecture of Tiahuanaco, including its appearance, rules of composition, canons, and production, filling a significant gap in the understanding of Tiahuanaco's material culture. Detailed analyses of building stones yield insights into the architecture of Tiahuanaco, including its appearance, rules of composition, canons, and production, filling a significant gap in the understanding of Tiahuanaco's material culture. Jean-Pierre Protzen , professor emeritus of the Department of Architecture at the University of California at Berkeley, has written extensively on the architectural and construction practices of the Inca. Stella Nair , assistant professor of the Department of Art History at the University of California at Los Angeles, has published on Inca architecture, Tiahuanaco construction, and Colonial Andean paintings.