Antonio Cavagna Sangiuliani (1843-1913) was a public official, book collector, and recognized authority on the history of the Lombardy and Piedmont regions in northern Italy. His library contained tens of thousands of books on history, genealogy, biography, and law, including city statutes and organizational bylaws. The manuscripts in the collection especially reflect the study of local history and include charters, chronicles, investitures, leases, and other legal instruments relating to Italian cities, organizations, and families.

All aspects of Italian history, from the Middle Ages to the first years of the twentieth century, are prominently represented in the Cavagna Sangiuliani Collection. Other topics which are heavily represented include art and architecture, church history and hagiography, engineering and fortification, military and religious orders, monasticism and religious life, Roman history and antiquities, and Italian academies and universities.

Primarily in Italian, the collection also contains works in Latin, French, and German. Among the books in the collection are incunables, rare and early printed books, pamphlets, and ephemera. Many of the historical documents are unique and found in no other library worldwide. In addition, the Cavagna Sangiuliani Collection also contains several thousand maps, both printed and manuscript.