The Manuscripts heritage houses more than 900 thousand documents, including personal, institutional, historical archives and literary works, many of the Brazilian literature important authors, such as Lima Barreto, Carlos Drummond de Andrade and Euclides da Cunha, among others. The originals, dated since the 11th century until the present, encompass both individual and bound pieces.

The items of greatest historical relevance come from the Royal Library and were brought to Brazil by the Royal Portuguese family in 1808. Since then, the heritage is in constant growth and congregates manuscripts in archaic, classic and contemporary Portuguese, Greek, Latin and Persian, with the most varied types of writing and media.

More than 240 registered and catalogued collections are available for consultation, each of them with its detailed inventory.

Sophisticated techniques are used for the study of particular documents, such as paleography - study of old writings, which helps deciphering very difficult texts, apparently unreadable for untrained eyes, as for example, Pero Vaz de Caminha letter.

Documents preservation requires special constant care and its cataloging is made according to the conservation state and physical condition. For being a very fragile media, the paper is handled with proper gloves. The originals are conditioned in layers with neutral pH and kept in sliding archives, in proper drawers for their conservation. Paperclips and other metallic objects are removed to prevent oxidation to endanger or worsen the state of pieces.