Columbiana is a city and the county seat of Shelby County, Alabama, United States. At the 2020 census, the population was 4,462. Columbiana, originally called Columbia, was selected as the county seat of Shelby County in 1826 over rivals Calera and Montevallo. After the selection as the county seat, Columbiana celebrated by drilling holes in a large pine tree and packing it with gunpowder. The tree was blown up and the sound could be heard for miles. Later in 1826, the courthouse was moved to an old school building in Columbiana.