The Castello Sforzesco Photographic Archives is one of the greatest in Italy by virtue of the quality and quality of the material held, the specific nature of the subject matter and the importance of the photographers included. Founded at the beginning of the 20th century, it now possesses approximately 850,000 original photographs ranging in time from 1840 to the present. The images captured by major Italian and foreign photographers using a whole variety of particular photographic and printing techniques include slices of social history, ways of life, portraits of famous people, natural landscapes, episodes of urban transformation especially in Milan (the rebuilding of the Castello Sforza), precious items of artistic heritage, and series devoted to travels in the East during the 19th century (the Ottoman Empire, India, China and Japan) and historical events (the Roman Republic of 1849, the Crimean War of 1855, the Milanese riots of 1898). The sections of greatest historical importance include the Luca Beltrami Collection, the Iconographic Collection and the Lamberto Vitali Collection. The archives is today involved in projects for the conservation, restoration, scientific cataloguing and digital acquisition of the images so as to make its holdings more readily accessible also via computer. The photographic collections are entirely available on a daily basis to the public in the reading room, which periodically hosts lectures and exhibitions on the history of photography. The archives also has an organized collection of specialized publications and periodicals, the catalogue of which is now accessible on the OPAC (On-line Public Access Catalogue) of the Lombardy Region through the SBN (national library) network. In addition to specialized and often hard to find books on the history and technique of photography, the library includes a rare collection of 19th century sales catalogues of photographic studies (including Alinari, Brogi and Anderson in particular).