Dürer’s Underweysung der Messung (1525, 1538) is most famous for having introduced the rules of linear perspective north of the Alps, and his engraving The Painter with a Lute at the end of the book stands as an emblem for a Renaissance culture of perspective. This Working Group project focused, not so much on what Piero della Francesca called prospectiva pingendi or on Albertian perspective, but more broadly on a variety of practices sited at the nexus of geometry, surveying, optics, perspective, and architecture. These practices can be encompassed under the polysemic term Messung (or measurement), used by Dürer. They include of course linear perspective, but also the range of shadows, mirrors, optical devices, polyhedra, as well as optics applied to the measurement of distances. The use of more or less simple instruments and the preparation of templates are often characteristic of the procedures described. The core of the Working Group book chapter was dedicated to the study of the context-dependent meanings of perspectiva in Dürer’s writings (manuscript and print), as compared to Messung, as well as of its circulation in sixteenth-century Southern Germany. The main source material to be examined here consisted of the so-called Kunstbüchlein, written by artists and artisans with reference to Dürer’s manual, from Johann II von Simmern 1531 to Paul Pfintzing 1598-9 and Johannes Faulhaber 1610, the latter two building at the turn of the seventeenth century a German tradition starting with Dürer, and including Augustin Hirschvogel 1543, Hans Lencker 1571, and others. Questions included at what point and where perspectiva was used in the surveying tradition and in architectural contexts.