As part of the P16901-G06 project, which was financed by the FWF (Austrian Science Fund), the complete writings of Camillo Sitte are being published for the first time ever in a six-volume edition, including critical apparatus. The basis for this edition is the Archive of the Sitte Estate, which is in the ownership of the Technical University of Vienna. The 17 pieces included in Volume 5 comprise the work in the field of art theory and art history that Camillo Sitte published over a period of three-and-a-half decades between 1868 and 1903/04. They include four extensive autographs, four special publications, seven articles in specialist journals and newspapers, as well as a table and a letter. All the documents are preserved in the Archive of the Sitte Estate. The writings published in Volume 5 show Sitte on the one hand discussing questions of art theory as a universalistic theorist whose studies had included the latest developments in the natural sciences, epistemology and physiology. On the other hand, they demonstrate Sitte`s influence as an art historian. The main topics of his writings on art theory are perspective, colour, anatomy and proportion. The results of physiological research are employed to explain human perceptual mechanisms (`Goldener Schnitt`), while historical lines of development (`Perspektivisches Zeichnen`, `Farbenharmonie`) are traced in order to serve as the basis for Sitte`s pedagogical concepts. Of exceptional importance is a two-part autograph, published here for the first time ever, which delineates the history of perspectival drawing and Sitte`s reflections on the teaching of draughtmanship. The subject of "perspective" is furthermore treated in the essays `Beobachtungen über bildende Kunst` (1868) and `Die Perspectivlehre des Pietro degli Franceschi` (1879). The subject of "colourfulness" is dealt with in two essays: `Über Farbenharmonie` (1900) and `Über die Bemalung figuraler Plastik im griechischen Alterthume` (1898). Sitte`s knowledge of anatomy and his interest in the structure of the human figure are brought together in a compilation entitled `Topographische Anatomie` (no date), which is published in the form of excerpts. The extensively illustrated original manuscript `Vorträge über Geschichte der Baustyle` (1883-84) presents the development of architecture from ancient Egypt to the Romans and provides evidence of the studies undertaken by Sitte in the history of architecture. In two introductory essays, Robert Stalla and Mario Schwarz contextualise the edited writings and examine the overriding considerations. In the process, a picture of Sitte as a universalist becomes more clearly discernible, as does the significant influence of Rudolf von Eitelberger (Stalla); Sitte`s doctrine of architectural styles is also investigated and classified (Schwarz). Brief editorial introductions and accompanying commentaries contribute to the understanding of the source texts. The series editors of the Camillo Sitte Complete Works are Klaus Semsroth, Michael Mönninger and Christiane C. Collins.