- Keene is a city located in Cheshire County, New Hampshire, United States. It is the county seat and the largest city in the county. As of the 2020 census, the population of Keene was approximately 23,700. The city is known for its rich history, picturesque landscapes, and vibrant cultural scene. Keene is home to several educational institutions, including Keene State College. The city is also famous for its annual pumpkin festival, which attracts thousands of visitors every year.