Mapping Cults of Christ’s Holy Blood
in Late Medieval and Early Modern Europe

This project was undertaken as part of a seminar with Alison Langmead on “The Digital and the Humanities” during my first semester as a graduate student at the University of Pittsburgh (2015).

The adventure began in 2013 when one relic of Christ’s Passion grabbed my attention, Holy Blood. It appeared in numerous forms and was the subject of debates that struck to the core of the Christian faith. From reading Caroline Walker Bynum and Mitchell Merback, I knew that there was no “reliable” survey of Holy Blood Churches. I wanted to take on that project. 

Paper Map
The paper map that I created at home 2013-2015 

I had two goals in mind, to organize the information I was collecting and find a way to accurately place that information on the “planet” to see if relic types were common in one region over another. I was originally doing this with colored pins on a giant paper map. Before long, I began to draw important boarders its surface. Then I pinned historical maps on the board. I even connected some points with string if a well-traveled pilgrimage route ran between them. Below this giant map, I was making a timeline with notecards. This became cluttered very quickly, and was unavoidably imprecise. 

At the same time, I began to compile information on sites that boasted a relic of Christ’s Blood, either miraculously appearing or historically collected at Calvary. For over a year, I gathered attention-grabbing information into an Excel spreadsheet. This flat-file database was organized and color-coded by region, but had a lot of missing information that translated into blank fields.

Early Spreadsheet 2013-2015

That semester, I crafted my first question, which I hoped to address through the use of digital tools. That initial line of inquiry was, “What patterns are there in the locations of cults dedicated to the veneration of Christ’s Holy Blood from the twelfth to fifteenth century?” From the very beginning of this project, I was interested in using a map to visualize the corpus of such churches. I was inspired by the Mapping Gothic France project by Stephen Murray at Columbia University. The use of maps, images, measurements, and text seemed to be the best way to archive and explore such a large group of architectural spaces. I had no idea how much effort was behind the front end that is viewable today. I needed to begin my project somewhere else. 

My spreadsheet was the logical starting point. The color-coding system was not as helpful as I had hoped, and I needed to address the growing number of columns and blank cells in this early version. That first flat-file database was created without forethought about what information should be collected or used. In some cases, I neglected to record my sources, a problem which continues to haunt me. 


My first project product this semester was a new and improved “Normalized Flat- File Database” with no blanks. To eliminate blank cells, “TBD” was inserted in fields that required further research, and “Unknown” was used if there was scholarship that identified missing information on that topic. Though I provided for such an occurrence, it had not applied to more than two sites. Drop down value sets were created to prevent typos. This way, I could search or sort with relative confidence that I would gather what was needed. 

Normalized Spreadsheet, Iteration 1 of 2015 Project

Even though I only used Excel for the first iteration, I learned a lot about creating a digital project. These fundamental lessons were a result of the decision making process. Choices made about columns and their contents required engagement with matters of terminology and categorization. For example, I had to decide what my value sets would be, and define terms such as “blood host” or “wonder host.” Something had to be done with the blanks, so that I would know if the information was deleted, it was not found, or if it did not apply. What “did not apply” had to be in one group, and so if my terms failed to capture what I needed to say, I had to reevaluate. 


After the first iteration, my question changed slightly to read, “What patterns of geographic concentration are there in the location of cults dedicated to the veneration of Christ’s Holy Blood from the twelfth to the fifteenth century?” The significant change was adding the term “geographic concentration.” Upon reflection, I believed that clusters of a “type” would be more likely and appropriate than the vague term “pattern.” I soon commenced with my second tool, Google Fusion Tables, to visualize these points and potential clusters. A butterfly tutorial indicated how to map points on the planet, and pull up information about the point. Since I wanted to be able to see the types of relics in different colors, I appreciated the variety of points available in this tool. 

I then began working with a small set, ten sites, from my spreadsheet. After figuring out how to get the tool to recognize my latitude and longitude, I explored the features. I knew this information better than the butterfly example, and I learned how to get the tool to “understand” each of my column headings. The cards feature did not seem to be something I needed, but it was an interesting way to view each site by itself. I tried to color code by relic type, but ran into trouble. I colored the sites by year at first, because Fusion Tables would only “bucket” by numbers. No obvious patterns were revealed from that endeavor. 

Trial Run with Limited Sites

Once I felt comfortable with a few of the features, I went “all in” and uploaded the entire spreadsheet of sites. One of the points displayed in Africa, which happened because a tens value went missing. I probably deleted it accidentally. It was exciting to see those red dots pop up! When I tried to separate them by relic type, I ran into the same problem as the trial run. Google only allowed me to separate out groups by numbers. I really wanted to sort by my drop down value sets, of which I was quite proud. Alas, it was not meant to be. I had to find a way to work around the numbers requirement, and get the tool to show what I wanted. I was not interested in sorting by date, but I tried color-coding by year with this full set since it was not difficult. Once again, when I did sort by date, I was not struck by what I saw. 

Left: All of the sites without color-coded points.
Top Right: The spreadsheet uploaded online. Bottom Right: The cards that display each site individually. 

It took me a short while to figure out a solution to my point problem. I assigned numbers to the relic types. There are eleven types in my dropdown value set, but two of them can be colored the same (TBD and Unknown). Therefore, I needed just ten colors or different icons to display on the map. My values were separated conveniently from my original sketch of the value set, with communion wafers on one end, and all remaining blood relics on the other end. I counted by tens, incase I needed to place a new relic type in between two existing labels. I wrote all of the types and numbers down on a post-it. 

First Color Coded Map by Relic Type

When I saw this map, the huge cluster of color thrilled me. However, I quickly realized that many of these points have uncertain relic types. That meant that the color was telling me that I am missing a lot of information. Then I noticed the gap, which has a many possible reasons for existing. It looks like there are groups in the north and the south, but few in the middle. It may be that I just have only encountered texts that name sites in these regions, it might be a result of an area of destruction from the Reformation, or any number of wars fought in Europe over the last six hundred years. It might be that the north and south were just more able to support the construction of a church of this type during these centuries. These are some of the possibilities I hope to explore in the future. 

I found that this tool, Google Fusion Tables, did not make it easy to track my column on violence in relation to the miracle origin legend. I also wanted to overlay political borders, which is possible with this tool through the use of polygons. Rather than work with rigid shapes like this, illustrating these boarders will likely be one of my next steps in another tool as this project continues. 


Some might not consider the tools and capta I used to be “DHTM”, but both pushed my understanding and skills. I primarily used a flat-file database for most of the work. I also mapped using Google Fusion Tables and performed “traditional” art history, such as researching and reading. Many of the indispensable texts are in German or a dialect of the language, and require a reading skill I hope to continually improve alongside my digital methods. 

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