The Biblioteca del Capitolo Metropolitano is the oldest library related to the Cathedral of Milan.
The library collections, which include 9th-century MSS, are particularly important for the history of
the Ambrosian liturgy. Documents preserved in the archive of the Metropolitan Chapter of Milan
shed light on the history of the library since the death of saint Charles Borromeo (1584) until the
20th century. Most relevant sources are the series of minutes of the Chapter meetings; the canons
deliberated over the library administration. Cash-books provide information on bequests, acquisitions,
expenses for maintenance and cataloguing, etc. Other documents are letters of scholars asking permission
to study MSS: among these G.P. Puricelli, M. Lupo, G. Tiraboschi, M. Magistretti, A. Ratti (Pio XI).