There has been a Library at St John's ever since the College's foundation. Originally it was in a wing adjoining the Great Gate, but in the 1620s work was undertaken on a new building to house its growing collections. It is this building which forms the northern range of Third Court, and which is now known as the Old Library. The collections held in the Library have been assembled over five hundred years, and include many fine illuminated manuscripts, fascinating early printed books, and other important historical documents, such as the papers of its alumni.
Entrance is now obtained through the newer Working Library, off of Chapel Court, designed to provide a congenial working environment for modern users by Edward Cullinan Architects, and opened in 1994.