The Historical Civic Archive and Trivulziana Library , an institute created following the annexation of the Trivulzio collection to the pre-existing Historical Civic Archive of Milan , has been protecting, enhancing, promoting and increasing its documentary heritage and book collections since 1935.

The Historical Civic Archive and Trivulziana Library currently possesses over 1300 manuscripts, 1300 incunabula, 16,000 sixteenth-century editions, over 180,000 printed editions . The documentary heritage has instead reached about 1280 meters of linear development. Bibliographic repertories, manuals of philology, linguistics, palaeography, history of Milan and history of printing, constantly updated, are also made available to scholars, in order to offer material to aid in the research and study of the collections.

The Historical Civic Archive and Trivulziana Library also possesses a rich collection of Italian and foreign periodicals, of which over 150 are active. Currently the collection includes manuscripts , incunabula , sixteenth century , old printed books and modern editions. The oldest codex dates back to the eighth century, while the most famous is Leonardo da Vinci 's notebook; noteworthy are Dante's manuscripts, including a codex of the Commedia of 1337 and a precious fourteenth-century manuscript of De vulgari eloquentia; finally, among the incunabula there is the complete collection of the fifteenth-century editions of Dante's Commedia .