Byzantine Studies, the field of the Humanities which investigates the history and culture of the Eastern Christian medieval empire centred upon Constantinople (4th to 15th C.), have been historically forged by cooperation between French and German scholars. Compared to the Classical and Western medieval world, Byzantium suffers from a lack of documentary evidence: however, while very few documents have been preserved, the seals which accompanied them have survived in large numbers and hold a great deal of information. These seals are the object of research of Byzantine sigillography, but their dispersal in scattered collections and the absence of widely shared standards for their publication has hindered the exploitation of their full potential for Byzantine Studies. The aim of this Franco-German project is to make use of the new capacities of digital presentation offered by the Digital Humanities to redress this situation, and to enable new understandings of Byzantium by transforming Byzantine sigillography. The core of the project will be the scholarly edition and publication of four major collections of seals (ca. 4.000 seals). On these collections extensive historical and sigillographic analysis will be performed: each seal will be studied as a research object per se through individual editions, while the edited corpora as a whole will be investigated through a number of targeted historical studies. Encoding these collections will enable us to build on work already done by the team to develop an encoding standard for seals (SigiDoc): we will test and improve this standard against the different requirements of these four collections. We will transform the reading and presentation of individual seals by the use of Reflectance Transformation Imaging (RTI) and exploit a range of resources to draw on external information—such as geodata—and make each item available as Linked Open Data. Finally, we will develop and test the use of a common centralised sigillographic portal allowing for global cross-corpus search. Concern is frequently expressed about the sustainability of digital resources. We aim to address this in two ways: our resources will be conserved by the Très Grande Infrastructure de Recherche (TGIR) Huma-Num and the Data Center for the Humanities (DCH) in Cologne, which partakes in the Nationale Forschungsdateninfrastruktur (NFDI). But, perhaps more importantly, we will ensure extensive knowledge exchange; we will work with curators to enable them to manage and enrich their holdings and to reach a wider public; and we will train scholars, curators, and students to use all our tools for their own research, in order to create individual publications which can be searched through our common sigillographic portal. In this way we aim to embed new tools and new skills within the study of Byzantium.