The Greater Philadelphia GeoHistory Network (GPGN) is a project by the Philadelphia Area Consortium of Special Collections Libraries designed "to develop a web-based repository of geographically organized historical information about Philadelphia, its geography, its buildings, and its people." It's quite an impressive endeavor, and anyone with a love for the City of Brotherly Love will want to spend at least a few hours on the site. First-time visitors can get started by clicking on the Resource Browser on the homepage. Here they will have access to thousands of digitized materials, including early images of the city, planning documents, historic views, land use maps, and so on. The items here date from 1683 to the late 1960s, and visitors can use the resource type toggle feature to look for specific groups of documents. Moving on, visitors can also use the Interactive Maps Viewer to look over map layers that include a 1934 land value appraisal map and a 1942 land use map created by the Works Progress Administration. Finally, visitors shouldn't miss the Educational Resources area. Here they will find guides for teachers seeking to use this wealth of information in their own classrooms.