The second volume of 'Leonardo Studies' hosts a dual theme of nature and architecture, offering a wide-ranging overview of current Leonardo scholarship on these two abundant subjects. While Leonardo worked his Treatise on Painting, he noted that understanding the physical properties of nature must precede individual projects of painting or designing buildings. The volume begins with the Trattato, and follows with physics, geology, painting that imitates architectural structure and vice-versa, and proceeds to architectural projects, questions of attribution, urban planning, and and the dissemination of Leonardo's writings in the Trattato and its historiography. This impressive group of articles constitutes not only new research, but also a departure point for future studies on these topics.