Lisbon is a town in New London County, Connecticut, United States. The population was 4,338 at the 2010 census. The town center is also known as the village of Newent. The town school is Lisbon Central School. Lisbon has one of the weakest municipal identity foundations in Connecticut. Its only postal code, 06351, is Jewett City, Connecticut, which is a village of the town of Griswold, Connecticut and encompasses all of Lisbon and Griswold.