The collection of manuscript maps of the Biblioteca Nacional is of great interest. Many of them, the most important, are in the Manuscripts Service, included in different works; also preserved are Portolan charts, maps and charts on separate sheets. The largest collection is in the Cartography Service and consists of maps originating from the First Secretary of State. Also part of this magnificent collection are the maps originating from the Royal Library and the Garat López bequest.

They consist mostly of eighteenth century maps drawn by military engineers. The subject matter is very varied, since the Ministry of State deals with matters as wide ranging as foreign relations, health, public works, postal services, roads and canals, shipping companies, etc.