This project developed certain ideas first explored in Dominion of the Eye. It studied the appropriation of the ancient/medieval science of optics in Italian architecture and urbanism. Although the onset of such "optical" architectural influence is often dated to the Quattrocento, an earlier date is far more probable. This re-dating only stands to reason, given that it was the Trecento, not the Quattrocento, that saw the creation of buildings and piazzas of unprecedented scale, which virtually demanded a heightened attentiveness to the problematics of perception.
For Trecento architects, the building was not an autonomous form. Its concrete visual perception, as construed in the eye of the observer, was highly curated in two ways, which the author terms "Vitruvian" and "Euclidean." In the first, following the Vitruvian doctrine of prospectiva aedificandi, the building itself was shaped toward conditions of visibility. In the second, the conditions of visibility themselves were configured in shaping the viewing space (or piazza). Here, the positioning of the viewer and the framing of their view appear to have been ultimately guided by contemporary optical theory originating in Euclid. In some instances, the resulting viewing space so closely conformed to scientific parameters regarding the image of the building in the eye of the beholder that the resulting space can fairly be called a Euclidean piazza. But the two sides of the equation, regarding the building "itself" and the viewer’s eye, were not disassociated—they tended to develop interactively. In at least one notable instance, Vitruvian inflection of the proportions of the building was interwoven with the Euclidean determination of the viewer’s eyepoint with perfect conformity to both theoretical models.
A third strand in this planning movement involved surveying theory, and its relationship to the optical technique of the visual measurement of size. As a widely diffused component of Trecento visual theory in the literate community, it may have served as an important intermediary in the movement of optics from high theoretical discourse into the area of public experience, which was the matrix of architecture and urbanistic practice.