David Rumsey, with Humphrey Southall (University of Portsmouth) and Petr Pridal (Moravian Library) led a presentation at AAG introducing a new website: oldmapsonline.org. The website's goal is to provide a clearer way to find old maps, and provide them with a stable digital reference. As David says: hundreds of thousands of historical maps have now been scanned and made available on-line by libraries around the world, and this has been a great boon to anyone interested in the history of cartography. However, those interested in the history of the places shown on maps have been less well served: just because a map is "on the web" does not mean we can find the relevant library web site, and even when we find the site the available catalogues are little help in finding maps covering particular places. A further problem is that even when digitized historical maps have been made available via geo-spatially aware online systems, the resulting references,i.e. the Uniform Resource Locators for accessing the maps, are generally very technology-dependent and unlikely to work even a few years later. The Old Maps Online project provides a universal search portal for historic maps designed to complement rather than compete with libraries' own search interfaces, and also developing best practices for defining persistent Uniform Resource Identifiers for historic maps - URIs not URLs.