The main University Library is one of the six legal deposit libraries under UK law, the others being the British Library, the National Library of Scotland, the National Library of Wales, the Bodleian Libraries, Oxford, and the Library of Trinity College, Dublin. Although the Irish Free State left the UK in 1922, Trinity College remains a UK deposit library and the UK libraries reciprocally retain deposit rights for Irish publications.
Through legal deposit, purchase and donation it receives around 100,000 items every year. The main University Library is unique among the legal deposit libraries in keeping a large proportion of its material on open access and in allowing some categories of reader (for example Cambridge academics, postgraduates and undergraduates) to borrow from its collections. The main University Library holds approximately 8 million items (including maps and sheet music).
Its original location was the University's "Old Schools" near Senate House until it outgrew the space there and a new library building was constructed in the 1930s. The library took over the site of a First World War military hospital, the "First Eastern General", on the western edge of Cambridge city centre, now between Robinson College and Memorial Court, Clare College.
The current librarian is Dr Jessica Gardner.
As early as the fourteenth century, Cambridge University owned a collection of manuscripts and some printed books. These would have been kept in chests along with other valuables, rather than in a library building as would be recognised today.