EC Library Guide to information on the European integration history: EU Libraries and Archives

EU institutions offer a variety of physical and digital libraries and archives providing access to historical collections.

Libraries of the EU institutions
The libraries of the EU institutions hold historical and contemporary material on European history.

EC Library

EP Library

Council Library

Library Court of Justice of the European Union

ECA Library

Documentation centre of the European Committee of the Regions (CoR)

European Economic and Social Committee Information Centre
Historical archives of the EU institutions
The historical archives of the EU institutions hold public documents that record decisions and findings that helped shape the EU. This website provides a complete list of these historical archives.
European University Institute (EUI)
The European University Institute, founded in 1972, is the leading institute in Europe dedicated to social sciences and humanities, including the history of Europe. It offers a variety of databases and information sources.

See for example

EUI Library

Historical Archives of the European Union: HAEU Online Exhibitions

Cadmus: the European University Institute research repository