Some of the most famous documents that the Archives preserve include the Cartola de accepto mundio, the oldest Italian parchment preserved in any Italian State Archives (dating back to 721); the Codicetto di Lodi; autographed letters from Leonardo da Vinci, Charles V, Ludovico il Moro and Alessandro Volta; a valuable copy of the Napoleonic Code autographed by the emperor himself; and the minutes of the trial against Gaetano Bresci.

[2] The decision to move from the old to the new location was dictated by the dual desire of the archivist Ilario Corte (1723-1786) and Emperor Joseph II's minister plenipotentiary, Wenzel Anton von Kaunitz-Rietberg, to secure the documents from the perilous Castello Sforzesco,[6] but also to "rationalize" the state's documentary heritage according to the principles of rational organization of the Enlightenment temperament according to the method of ordering by subject matter that would later find a radicalization in the work of Corti's pupil, Luca Peroni.

Built by Federico Borromeo in 1608 with a seminary established thirty years earlier by St. Charles (1579) for the special training of priests who would carry out their pastoral ministry in the Swiss valleys imbued with Calvinist doctrine,[18] the building, under Napoleon's Italic reign, between 1809 and 1814, housed the seat of the royal senate.

[19] The director's desire, however, had to run up against bureaucratic and technical impediments that lingered for more than two decades, so much so that Osio's successor, the historian Cesare Cantù, remarked in the early 1880s that there was still considerable slowness in the fulfillment of his predecessor's intentions.

[note 1] Above all, Luigi Fumi (director since 1907), assisted by Giovanni Vittani (who would be his successor from 1920), would initiate a process of modernization of archival science that would be reflected both in the teaching of the school (as will be explained in the section on it), and in the break with the Peronian system that still reigned under Osio and Cantù, using as the "scientific" voice of the institute's activities the magazine Annuario del Regio archivio di stato di Milano,[24] published between 1911 and 1919.

"[37] From the 1876 edition of the Lombardy Historical Archives, it is revealed that various historical, genealogical, diplomatic and heraldic works were donated to the Library: the description of the works for the drying of Lake Fucino; two books by Damiano Muoni Tunisi, Expedition of Charles V Emperor and Family of the Isei; a book by the cosmographer Vincenzo Maria Coronelli, Armi, Blasoni e Insegne gentilizie delle famiglie patricizie di Venezia; the VIth volume of the documents collected by the Society of Deputation over the studies of Tuscan, Umbrian and Marche Homeland History; and others.

[39] With the help of the stock register and topographical inventory (other "technical" sources relating to purchases and donations in the period before 1943) one learns of the patrimonial wealth achieved by the library: a rich section dedicated to law, volumes devoted to the history of the ancient pre-unitary states (Degli Statuti ciuili della Serenissima Republica di Genoua and the Diarii di Marino Sanudo il Giovane), art history, heraldry (Le leggi del blasone or L'arte vera dell'arme diuisa in due parti, by Louis De Lespine de Mailly), history (the Correspondance de Napoléon I) and archival, diplomatic and paleographic sciences.

[42] During the 1950s and 1960s, in addition to the purchase of more recent volumes devoted to archival and related sciences, efforts were also made to "proceed - compatibly with economic resources - to purchase recently lost volumes",[43] such as Pompeo Litta's Le famiglie nobili italiane[43] or the important diplomatic treatise Nouveau traité de diplomatique, ou l'on examine les fondements de cet art by Charles Francois Toustain and René Prosper Tassin.

[44] However, over the past seventy years, the library returned to its former glory as a result both of purchases made by the Archives and generous donations from private individuals that brought the institution to a count of 40,000 monographs, 300 periodical titles and 15.

In this popularizing perspective, Archeion also works to help candidates for admission into the School of Archival Studies, Paleography and Diplomatics to approach medieval Latin, the language they will have to translate in the exam.

The oldest parchment document preserved (not only in Milan, but also in the rest of the other State Archives) dates back to May 12, 721 and is entitled "Cartola de accepto mundio.

Peroni, moved by the Enlightenment rationalization initiated by Encyclopédie and the classification of the animal and plant world by Carl Linnaeus,[59] proceeded to dismember the original archives and then to select or discard the said papers and finally re-aggregate them according to subject matter.

[60] Although this inevitably entailed breaking the archival bond, the Peronian system was introduced as an act of an administrative nature: the adoption of a single criterion of organization by subject matter would allow records to be found quickly and efficiently.

[64] This designation refers to the archives that came into being and were produced as a result of the political-institutional changes that occurred after the geopolitical restructuring of central and northern Italy first by the French revolutionaries and then by Napoleon Bonaparte.

[69] Of relevant interest are the papers grouped in the fund Political Trials, aimed at targeting Carbonari, members of the Mazzinian-inspired Giovine Italia and patriots in general.

[71] At the moment, this archive no longer exists as such, however, the collections: Diplomatic Museum, Diplomas and Sovereign Dispatches, Short Bulls and Parchments for funds still belong to it.

Having also organized this archive by subject, Luigi Fumi and his immediate successors attempted to bring back the old structure, but the war and the sheer volume that went into making up this fund did not allow the fulfillment of that will.

[100] However, in the legislation of the new unified state, the school was officially established in 1874 by royal decree March 26, 1861,[note 5] and classes were held in four hours a week ("on non-holiday Mondays and Thursdays")[100] and were accompanied by paleographic, diplomatic and archival exercises.

For this reason Cantù's successor, Count Ippolito Malaguzzi Valeri (1899-1905) insisted on a renewal of the curriculum studiorum,[104] but his untimely death did not give him time to make these changes.

"[105] Giovanni Vittani, assisted in this by archivist Giuseppe Bonelli and Cesare Manaresi, introduced the principles of archival science formulated in the late 19th century by the Dutchmen Muller, Fait and Fruin, whose manual was first printed in Italy in Turin in 1908.

[106] Famous were the prolusions that Vittani gave at the beginning of the academic year not only to the school but also to the Milanese cultural elite and which were later included in the Yearbook promoted by Fumi.

...we say that the senate authorised the notary Calchi to draw up the will, in the presence of a judge, a canon, three interpreters, seven witnesses and two prothonotaries [...].In the State Archives of Milan, directed by Mr. Cantù himself, the course of Palaeography and Diplomatics was closed this month and examinations were taken by those attending the school.

Mr Cantù found that the nature of this institution was eminently practical, since the school was intended to train not scholars but archivists, and therefore did not insist much on the theoretical part in the examinations.Underlying the system is the conviction that the subject matter is the most appropriate and most useful denominator for sorting archives, also for research purposesOut of the School were to come those young people who were to devote their professional day to archives.This branch of the ancient Milanese Bossi family added the Visconti surname to its own following the marriage of FRANCESCO to Isabella Visconti.