Ambrosian Library, a collection founded in Milan in 1609 by Cardinal Federigo Borromeo, archbishop of that city, and named in honor of St. Ambrose. It is especially rich in MSS., for the collection of which learned men were sent into all parts of Europe, and into Asia. A very large number of palimpsests belong to this library; some of them are exceedingly rare and valuable, among which may be mentioned Cicero's De Republica, fragments of his orations, and the letters of Marcus Aurelius and Fronto. The palimpsests were mostly obtained from the monastery of Bobbio, and were discovered by the librarian, Angelo Mai, in 1814. There is a MS. of Virgil, valuable for its marginal notes by Petrarch, among which is one relative to his first meeting with Laura. The library at present contains about 90,000 printed volumes and more than 15,000 MSS., besides a large collection of statuary, antiques, medals, and pictures. Among these are Raphael's cartoon of the "School of Athens " and the studies of Leonardo da Vinci. Many of the treasures of this library were carried to France during Napoleon's campaigns in Italy, and some of them have never been returned.
A printing press is connected with the library, and several professors and editors are constantly engaged in collating and translating the MSS.