The Ambrosia library is housed within the same building as the Pinacoteca Ambrosiana Museum. The two establishments were founded by Cardinal Federico Borromeo (1564-1631) and named after the patron saint of Milan. The library is famous for the structure as well as the books and manuscripts it holds. The cardinal was an avid art collector and bibliophile; he sent people out across Europe and Syria to collect valuable manuscripts, particularly those with some religious significance. He amassed over 30,000 manuscripts

Among the famous works in the library collection are manuscripts brought from the Monastery of Bobbio (1606) and from Vincenzo Pinelli's library, Pinelli was an Italian humanist and a mentor to Galileo, his collection included a 5^th century copy of Iliad. Other gems in the collection are the love letters of Lucrezia Borgia and Pietro Bembo as well as a lock of Lucrezia's golden hair; Dante's Divine Comedy (1353), Muratorian Canon (170AD), 1,750 drawings by da Vinci and manuscripts by Leonardo da Vinci including his Codex Atlanticus which were acquired after the Cardinal's death. The collection includes valuable drawings by European artists from the 14^th to 19^th century, Renaissance literaria and medieval manuscripts. The valuable books and manuscripts are in several languages including Hebrew, Syrian, Ethiopian, Arabic, Latin and Greek and cover a myriad of subjects. Many well known writers and poets have visited the library including Lord Byron and Mary Shelley. Visitors can enter both the Pinacoteca art galleries and the library for the same entrance fee.