What can a big data approach bring to the study of the early modern Republic of Letters? This is the question we asked ourselves in our collaborative project Mapping the Republic of Letters. For the past nine years, we have been exploring the limits and possibilities of computation and visualization for studying early modern correspondences, whose massive and dispersed character have long challenged their students. Beyond cliometrics, what new ways of discovery and analysis do today’s big data offer? What can we learn by visualizing the archives and databases that are increasingly accessible and viewable online? In a variety of case studies focusing on metadata (in the letters of John Locke, Athanasius Kircher, Benjamin Franklin, and Voltaire, and in the travels of those engaging in the Grand Tour), we experimented with visualizations to produce maps of the known and unknown quantities in our datasets, and to represent intellectual, cultural, and geographical boundaries. In the process, we experienced collaborative authorship, and worked with designers and programmers to create an open access suite of visualization tools specifically for humanities scholars, Palladio. What might the next research steps be, as linked data rapidly develops further possibilities?