The quintessential Renaissance Man, Leonardo da Vinci was well aware of the fundamental importance of mathematics for architecture. This issue of the Nexus Network Journal examines Leonardos knowledge of theoretical mathematics, explores how he used concepts of geometry in his designs for architectural projects, and reports on a real-life construction project using Leonardos principles. Authors include Sylvie Duvernoy, Kim Williams, Rinus Roelofs, Biagio Di Carlo, Mark Reynolds, João Pedro Xavier, Vesna Petresin, Christopher Glass, and Jane Burry. To complete the issue Rachel Fletcher writes her Geometers Angle column on "Dynamic Symmetry", Michael Ostwald reviews A Theory of General Ethics by Warwick Fox, Sarah Clough Edwards reviews Inigo Jones and the Classical Tradition by Christy Anderson, and Sylvie Duvernoy reviews Architecture and Mathematics in Ancient Egypt by Corinna Rossi.

Letter from the Guest Editor.- An Introduction to Leonardos Lattices.- Leonardo da Vinci: Architecture and Mathematics.- Transcription and Translation of Codex Atlanticus, fol. 899 v.- Two- and Three-Dimensional Constructions Based on Leonardo Grids.- The Wooden Roofs of Leonardo and New Structural Research.- Leonardo and Theoretical Mathematics.- The Octagon in Leonardos Drawings.- Leonardos Representational Technique for Centrally-Planned Temples.- Perception of Order and Ambiguity in Leonardos Design Concepts.- Leonardos Successors.- Geometers Angle.- Dynamic Root Rectangles Part Two: The Root-Two Rectangle and Design Applications.- Didactics.- The Other Mathematical Bridge.- Book Review.- Warwick Fox A Theory of General Ethics: Human Relationships, Nature, and the Built Environment.- Christy Anderson Inigo Jones and the Classical Tradition.- Corinna Rossi Architecture and Mathematics in Ancient Egypt.