The Old Sullivan County Courthouse was the first county courthouse of Sullivan County, New Hampshire. It is a 2-1/2 story Federal-style brick building in downtown Newport, the county seat, located on a hill above Main Street and behind a cluster of later civic buildings. It was built in 1825-26 (prior to the establishment of Sullivan County, which occurred in 1827) with funding from the town, and was instrumental in the choice of Newport as the new county's seat. The building served as a county court and town hall until 1873. It was used by the town as a school until 1896, when it was leased to the local Grange chapter.