From 1777 the building, built in the mid-500, was subjected to a long series of restoration and extension works entrusted to the architects F. Fuga and P. Schiantarelli.The floors can be reached by a great staircase and a lift.
Altogether, the Museum covers about 18.500 square meters, about 8.550 of which are used as exhibition spaces, placed on five floors: basement (Egyptian and Epigraphic Section), ground floor (Farnese Section), mezzanine (Mosaics, Secret Cabinet, Numismatics), first floor (Sections of Frescoes, Bronzes, Prehistory, Temple of Isis, Villa dei Papiri), second floor (Collection of Medals). Other 6.000 square meters are used as warehouses and about 3.400 square meters are used as offices and services (Library, Historical Archives, Restoration Laboratory).
The Historical Archives keep the documents relating to the life and the functioning of the “Real Museo Borbonico e Soprintendenza agli Scavi del Regno”, one of the most ancient museum institute of preservation in Europe. They have been subjected to several transformations in time – both in the title and in the range of competences – becoming “National” with the Unity of Italy.
The documents, which come from mid-700 to about 1920, concern two main activity fields: the Museum (including the Picture-gallery, transferred to the Museum of Capodimonte in 1957) and the excavations, beginning from the excavations of Pompeii, Herculaneum and Stabiae to other excavations carried out by Government and private citizens in many places in Southern Italy and in Campania.
At present, the Archives consist of about 12.000 files, 300 drawings and 180 handwritten volumes containing the ancient inventories of the Museum. All this material is catalogued in a data base and uses the ancient classification according to thematic and/or topographic categories which has been respected and re-established in the reorganization carried out in the last years.
The laboratory carries out its activity even thanks to some relations of cooperation at international level; for example, for a long time it has collaborated with Getty Conservation Institute in Los Angeles (USA), with which important restoration works have been carried out. These works have affected permanent collections of the Museum, such as “Apollo Saettante” coming from the excavations of Pompeii, the Statue of Tiberio coming from Herculaneum and finally an Apulian pot from Altamura. After the restoration, the findings are temporarily exhibited in the American museum.