The BNE is an outstanding collection of about 2.5 medieval codices, a third of whom approximately contain some kind of decoration. A notable feature of the collection is the great variety of Eras and schools.

From the ninth (Codex of Metz) until the 18th century in the manuscript illumination as form of artistic expression are testimonies in the rich and voluminous collection. All the european schools in lighting are represented (spanish, italian, french, english, various hotbeds of central europe) stressing, by their number and quality, the fund.