This paper discusses the ways in which Luca Pacioli established the body of architectural theory as a mirror of mathematical proportionality, the inner principles of the cosmos and universal harmony. During the last quarter of the 15th century the mathematician Pacioli met artists and architects such as Francesco di Giorgio Martini and Leonardo da Vinci. Pacioli’s De divina proportione reflects these acquaintances. The text, embedded in Euclidean and Neo-Platonic concepts, discusses a number of topics such as the golden ratio and the cosmic role of polyhedral solids. In its second part, Pacioli focuses on architecture and Vitruvius’ canon of proportion, which he interprets as the anthropomorphic and anthropometric matrix for the production ...