Cambridge is a city in and the county seat of Guernsey County, Ohio, United States. It lies in southeastern Ohio, in the Appalachian Plateau of the Appalachian Mountains. The population was 11,520 at the 2000 census. It is the principle city of the Cambridge Micropolitan Statistical Area. Cambridge is well-known among glass collectors as being the location for the Cambridge Glass, Boyd Glass and Mosser Glass plants. The Cambridge area is also famous for its "S" shaped bridges, some of the first bridges ever constructed in the Northwest Territory. It is located adjacent to the intersection of Interstates 70 and 77, which the Ohio Department of Transportation proclaimed in 1969 to be the world's largest interchange in terms of land area.