Epigraphic archives, containing collections of editions about ancient Greek and Latin inscriptions, have been created in several European countries during the last couple of centuries. Today, the project EAGLE (Europeana network of Ancient Greek and Latin Epigraphy, a Best Practice Network partially funded by the European Commission) aims at providing a single access point for the content of about 15 epigraphic archives, totaling about 1,5M digital objects. This paper illustrates some of the challenges encountered and their solution for the realization of the EAGLE data infrastructure. The challenges mainly concern the harmonization, interoperability and service integration issues caused by the aggregation of metadata from heterogeneous archives (different data models and metadata schemas, and exchange formats). EAGLE has defined a common data model for epigraphic information, into which data models from different archives can be optimally mapped. The data infrastructure is based on the D-NET software toolkit, capable of dealing with data collection, mapping, cleaning, indexing, and access provisioning through web portals or standard access protocols.