DECIMA: The Digitally Encoded Census Information and Mapping Archive, and the Project for a Geo-Spatial and Sensory Digital Map of Renaissance Florence

A project at the University of Toronto, with funding from the Social Sciences and Humanities Research Council of Canada (SSHRCC), is developing a mapping tool that will allow for the spatial organization of early modern historical, cultural, and sensory materials.¹ Called the Digitally Encoded Census Information and Mapping Archive (DECIMA), it uses Geographic Information Systems (GIS) software to map, house by house, a 1561-62 Florentine tax census onto one of the best city maps produced in the sixteenth century. This undertaking will allow scholars to understand the social geography of Renaissance Florence in dynamic ways, creating a highly adaptable ecosystem for the cultural analysis of a variety of problems and issues. One key advance is that this project aims not simply to computerize a fixed field of data, but also to develop a tool for the ongoing accumulation of material by scholars in different disciplines, chiefly history, art history, literature, and music. We also aim eventually to apply the experience developed in the Renaissance Florence map to extend the tool to other early modern cities with similar source materials. The DECIMA project contributes to the expansion of historical GIS with a large database of historical maps and accompanying datasets that will be accessible and expandable by a range of scholars.

DECIMA's project to create a digital map of Renaissance Florence integrates two sets of sources, one visual and one manuscript-based. The visual source is a late-sixteenth-century axonometric projection (often known as a "birds-eye-view") of the city of Florence. It was originally produced in 1584 by an Olivetan monk, Stefano Buonsignori, about whom little is known. Buonsignori employed the common survey techniques of the sixteenth century to produce a map that contemporaries recognized as exceptional, and that map was widely reproduced for over a century. The map's strengths make it an ideal source for digitization. It is large, printed in nine sheets, with the original measuring 123 x 138 cm. Using an extremely high-resolution digital reproduction, DECIMA researchers are able to zoom in to individual street and building level without sacrificing the quality of the image. The map is of sufficient accuracy that geo-referencing it in a GIS program has proven successful, although the limitations of Buonsignori's survey technique result in a slight skew of the spatial accuracy in the eastern edge of the city's southern Oltrarno district. Finally, although the drawn buildings are often impressionistic, particularly townhouses, Buonsignori was extremely careful in the drawing and locations of significant markers, including monasteries and convents as well as the city's churches, palaces, monuments, and city squares. This map forms the visual basis of the DECIMA Digital Map of Renaissance Florence.

The major text source for the DECIMA project is a 1561-62 tax census of Florence called the "Decima Granducale." This street-by-street, house-by-house tax census was commissioned by Duke Cosimo I, and it includes extensive information on the physical fabric and inhabitants of the city. The duke received a presentation copy in 1562 that is available in a modern reproduction.² The DECIMA project works with what were essentially the detailed notes made by the census takers over the previous year as they moved house by house through the city compiling data (held in the State Archive of Florence: Archivio di Stato di Firenze, 325, Decima Granducale 3780-3784). Their records account for the residents in each of the four quarters of the city (Santa Maria Novella, San Giovanni, Santa Croce, and Santo Spirito) and devote a separate volume to the city's workshops and places of business or botteghe (ASF, 325, Decima Granducale 3784). The census takers were assiduous in noting their route and methodology, with each entry linked to the entries above and below it via a description of the building's relationship to its surrounding buildings, e.g. whether it is attached to a building next door, is free-standing, or is the end of a section of...