The oldest documents in the archive are associated with what is known as the founding collection (works from the National Library, the Royal Cabinet of Natural History and the Spanish School of Diplomatics), which was joined by the museum’s own administrative documentation when the institution began generating its own files in 1867.
In addition to these files, the archive contains other resources of tremendous value that document the history of the museum’s collections, such as the old registrar logbooks and an extensive series of inventory, catalogue and registrar forms for the pieces displayed in the galleries and for different themes.
The archive also houses documents containing fascinating information, some of which are personal archives in themselves, comprising correspondence, pre-publication projects, lectures and even excavation drawings and notebooks. Some of the most interesting are the personal archives of Luis Siret, the documents belonging to Julio Martínez Santa Olalla, and others related to private collections such as those of the Marquis of Salamanca and Tomás Asensi, among others.
This vast repository of information is complemented by a large collection of maps, plans and drawings which document archaeological excavations in both Spain and abroad and the various architectural modifications made to the museum building throughout its history, as well as original labels and signage from temporary exhibitions held on these premises.