Altamont is a town in Grundy County, Tennessee, United States. The population was 1,045 at the 2010 census. It is the county seat of Grundy County.
Altamont was established in 1848 as a county seat for Grundy County, which had been created in 1844. Adrian Northcut, a prominent local farmer and military officer, was the prime advocate for the site's selection. The town's name comes from combining alto (meaning "altitude") and mont (meaning "mountain"). Although the Civil War somewhat stunted the town's growth, by 1870 Altamont's population had grown to 217.
Altamont has one of the oldest Mormon congregations in the southeastern United States. The congregation was formed in the 1890s, and a Mormon chapel was built in Northcutt Cove just north of Altamont in 1909. Shortly thereafter, several members of the congregation migrated to Altamont. A Mormon chapel was completed along Main Street in 1947, and a newer chapel was completed just off Viola Road in 1981.
In 1988, Altamont's school building was renovated and now houses the Altamont City Hall and the Altamont Library and Museum. The building was renamed the "Florence R. Scruggs Municipal Building" in 1996, after a long-time teacher at the school.
Altamont is located in north-central Grundy County at 35°26′2″N 85°43′57″W (35.433954, -85.732428).