Inaugurated on 8 December 1609 by Cardinal Federico Borromeo, who wished to donate to Milan one of the first true public libraries in the world, the Ambrosiana today contains about one million printed works (mainly incunabula and cinquecentine) and thirty-five thousand manuscripts. This Guide offers a wide selection of the most precious volumes preserved in this Library, housed in a large, typically seventeenth-century hall, at once austere and solemn. The manuscripts chosen have been selected for the value of their content or decoration. Of each, both the history and the subject matter are presented in a clear and accessible manner, as well as the most refined and representative miniatures.