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DECIMA: The Digitally-Encoded Census Information and Mapping Archive
by Colin Wilder

Terpstra, Nicholas. DECIMA: Digitally-Encoded Census Information and Mapping Archive. University of Toronto. 2014. <>.


DECIMA is a web-based interactive map of sixteenth-century Florence. The map itself is a digital surrogate of the famous, highly-detailed drawing made by the Olivetan monk Buonsignori in 1584. Beyond just visual reproduction of the historical cityscape, though, DECIMA also locates the information about occupation and property ownership for Florentines in the Santa Maria Novella quarter of the city recorded in the census of 1561, known as the “Decima Granducale” after its initiator, then Duke Cosimo I (1519–74).[1] Complete upload of the census for the other three quarters is promised by the project’s curators in the near future.

More particularly, DECIMA is an interactive map, meaning that the user can zoom in to view small parts of the image field of the Buonsignori map, down to the very house level. The exquisite detail and apparent accuracy of this period map and the high resolution of the map image scan make this possible. The DECIMA resource was created by a team, led by Nicholas Terpstra, at the Department of History and the Centre for Medieval Studies at the University of Toronto. The DECIMA team entered further data, including name, sex, address, occupation, and property ownership, for the roughly 10,000 households recorded in the census, and pegged each household to its street address on the map, including in apparently all cases Buonsignori’s representation of the period building itself. The user can approach this geographical and demographic data in two ways. He or she can browse spatially through the map, as it were flying around the streets like a bird and stopping anywhere to read the data from the census about a given location. Or he can search through the database using period terms like “calzolaio” (cobbler), to search for all the cobblers in Florence in 1561 and see where they lived.

The head of the project, Terpstra, is professor of history at the University of Toronto. His previous work, most recently Lost Girls: Sex and Death in Renaissance Florence,[2] has also been in the field of Florentine Renaissance social history. As is usually the case with scholarly digital projects, DECIMA is an avowedly collaborative effort. The other members of the team include four graduate students who transcribed the census data, put together the dataset and created the component digital map files (or base layers). This graduate student team was composed of Colin Rose, Eduardo Fabbro, Leah Faibisoff and Daniel Jamison. Finally, the DECIMA site (or portal) itself was coded by Andreea Gheorghe, Database Manager at the University of Toronto’s CHASS (Computing in the Humanities And Social Sciences) center. A team composition like this is of course typical for Digital Humanities projects, usually with a faculty lead chiefly responsible for design, proposal-writing, supervision and first-order scholarship; a research and clerical assistance team of student workers; and a technical team (in this case, just Gheorghe) responsible for the heavy lifting of the basic infrastructure creation. Such multi-party work is expensive and time-consuming, in Canada as much as in the United States and elsewhere. As is most commonly the case today, the project is paid for by the government (in this case, the Social Sciences and Humanities Research Council of Canada or SSHRCC).

The site functions smoothly, elegantly presenting the Buonsignori map and the Decima Granducale data. I would even say that the site is deceptively simple in that its basic functioning is to either pan and zoom or search the database fields; either method of navigation takes the user to the same endpoint, namely discovering one or more specific parings of map point and household census data. It is unfortunate that the site at present has no features for data export, which limits users to finding discrete data about one person or place at a time, with no convenient means of aggregating quantitative data, text from the database fields, or any particular map findings. It must also be understood that this is a data resource and does not constitute an interpretation of the source map or census data in any complex sense. Creation of digital resources like this can be considered “auxiliary” scholarly work (Hilfswissenschaften) on par with text collation or critical bibliography—a vitally necessary part of the overall life cycle of knowledge production, one that certainly requires scholarly training, but not attached to any published interpretation or argument. No doubt that will be forthcoming work by Terpstra, Rose et al in the near future, now that the hard foundational work has been done, much as a critical edition of a text must precede new analytic scholarship on it.

Work like this does not exist in a scholarly vacuum. DECIMA should be placed in at least two obvious contexts. One context is the editing and computational study of census and tax information for Renaissance Florence, work whose modern phase began with David Herlihy and his partners in the 1960’s in connection to the Florentine Catasto of 1427-1429. The abridged Online Catasto that developed out of this is currently hosted at Brown University.[3] More recent, also highly regarded work by John Padgett and Paul McLean has significantly extended our knowledge about Florentines over the fourteenth and fifteenth centuries, through the field of historical sociology and anthropology.[4] The other important context is that of comparable digital projects involving historical maps. The industry standard software for digital map-making is ArcGIS, a complex and powerful tool for curating geographical data, making maps and performing spatial statistics. All of this falls under the category of Geographical Information Systems (GIS). There is one major repository of published digital historical map files, namely the Historical GIS Clearinghouse and Forum of the Association of American Geographers.[5] As the latter’s name implies, though, it is only a clearinghouse for a hodgepodge of historical digital maps and geospatial data files from contexts all throughout world history.

This is where the future ambitions of the DECIMA team enter the picture. As articulated both in the DECIMA online documentation and by Terpstra and Rose in their published article describing the project, two significant future steps are planned. The first will enable export: The team plans to make it possible for users to export map images and data from a DECIMA user session. Hopefully this would include shapefiles and subsets of the database resulting from particular searches. The second will enable import: Terpstra and Rose write that DECIMA “will be a tool for the ongoing accumulation of material by scholars in different disciplines, chiefly history, art history, literature, and music. That is, researchers … will be able to add their data to it in such a way that the map continues to accumulate new layers of data and so steadily expands as an ever more sophisticated and useful research tool.”[6] Their ambition, which is most welcome, is for DECIMA to transcend sixteenth-century Florence and become a repository for sharing historical geographical data for cities all across Europe in the early modern period. 

No timeline has been announced for either of these plans. While this is unfortunate, it is not out of the ordinary. There is no publicly available information about the length or depth of SSHRCC’s funding of DECIMA, so it may well be that the team will need to seek continuation or bridge funding for these proposed next stages. This points of course to a major structural weakness of Digital Humanities, namely its dependence on special-project-based and non-native revenue sources for DH projects, making the future development and even ongoing maintenance of these projects precarious. But that is another story.


Colin Wilder
Center for Digital Humanities
University of South Carolina

[1] See project overview in Nicholas Terpstra and Colin Rose, “DECIMA: The Digitally Encoded Census Information and Mapping Archive, and the Project for a Geo-Spatial and Sensory Digital Map of Renaissance Florence,” Journal for Early Modern Cultural Studies 13.4 (2013): 156-60.

[2] Baltimore: Johns Hopkins UP, 2010.

[3] See David Herlihy and Christiane Klapisch-Zuber, Codebook of the 1427-29 Catasto Data File for Florence, and the Online Catasto itself (accessed May 9, 2014).

[4] For Pasdgett, see representatively “Robust Action and the Rise of the Medici, 1400-1434,” American Journal of Sociology 98.6 (1993): 1259-1319. For McLean, see The Art of the Network: Strategic Interaction and Patronage in Renaissance Florence (Durham, N.C.: Duke U P, 2007).  I was unable to find any English-language scholarship on the Decima Granducale.

[5] This appears to have incorporated Harvard’s former collection of historical GIS data.

[6] See Terpstra and Rose, p. 159



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Cite as:

Colin Wilder, "DECIMA: The Digitally-Encoded Census Information and Mapping Archive," Spenser Review 44.1.10 (Spring-Summer 2014). Accessed March 20th, 2018.
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