In the age of the WWW consistent efforts have been made to make information from the archives available for the general public to facilitate access to the wealth of documentary history for research, consultation or education purposes. Linked Open Data (LOD)[1] provide a well suited framework to expose archival content to the general public while enriching it with content from other sources. This paper describes the creation of the first of its kind linked open data prototype to access data from the Historical Archive of the European Commission (HAS), carried out within ISA² programme of the European Commission [2]. We present the designed ontology based on ISAD(G)[3], ISAAR(CPF)[4] and RIC-CM [5] models and the business processes of HAS, and the created knowledge base from a sample of HAS data, re-using authority lists from the Publication Office [6] and EuroVoc [7] and allowing querying via SPARQL endpoint [8].