On May 11, 2005, the online Encyclopedia of Chicago History went online, a multi-year collaborative effort of Northwestern University's Academic Technologies, the Chicago Historical Society, and the Newberry Library. This presentation will present the development process of the online encyclopedia, going on line six months after the print edition was published. It will detail the range of presentation models developed for building on the core of the printed edition, and bringing to bear the unique additions to the project to maximize a network-based presentation model built upon a database multimedia repository. 'Rich Maps' and 'Interpretative Digital Essays' authored by pre-eminent Chicago historians are two of the models that will be explored in this presentation that seeks to extend the experience of the printed edition. A large quantity of unique media was developed that enhanced and extended the presentation of this unique on-line resource. Custom image viewing applications, specialized photography, and the original creation of a single 3.3 gigabyte composite image of an 1886 Fire insurance map are among the specialized media developed specifically for the online edition.