Since its inception the National Historical Archive became established as the “historical archive of the kingdom of Spain”, an archive that is public in nature. It was set up to house the documentation produced by Central Government departments that no longer has administrative value but still has historical value. Currently, documents classed as historical must be deposited in the archive, having successfully passed the rational and compulsory screening processes stipulated by article 58 of the Spanish Historical Heritage Act.
Its functions are: to preserve and protect the documentary historical heritage that it already safeguards and the documents that ought to continue to be deposited (since it is an open archive); describe the information content of the documents, make the document collections accessible to both researchers and citizens, and promote the cultural dissemination of these documents. The National Historical Archive is the institution that preserves and safeguards the documentation produced and received by the entities that make up the administrative apparatus of the Spanish nation in modern times, in addition to other document collections of public and private institutions dating back to the Middle Ages.