Archives Portal Europe (APE) aggregates archival material from and about Europe, currently providing access to archival descriptions from more than 1,100 institutions of more than 30 countries in a single research point. It is currently the largest aggregator of its kind in the archives domain, and it aims to connect all archival collections related to the history of European countries, from the large state archives to local and private archives. The portal allows to conduct research with an unprecedented outlook based on cross-country archival comparisons and multilingual search. Thanks to this new tool, the functions indicated by Unsworth as “scholarly primitives” are available to researchers, and expressed in new forms. This workshop presents APE to both researchers and archivists as a tool that allows new types of historical research. Researchers will learn how to conduct research on APE in the most effective way possible; archivists will be presented with the metadata solutions applied by APE in order to provide the best possible returns to the users' search queries, while at the same time being sustainable and feasible for the partner institutions. This is embedded in a more general reflection on how metadata can inform researchers, connecting the work on APE with DARIAH's Working Group on Sustainable publishing of (meta)data, DARIAH's involvement in the Social Sciences and Humanities Open Cloud (SSHOC) project, and the Parthenos project. Following the individual presentations, speakers and attendees will be invited to reflect together on the role of metadata and cloud computing in digital archival research, and how archivists and researchers can collaborate to make digital archives as open as possible by improving searchability and retrievability.