Andersonville National Historic Site

The Andersonville prison, located at Camp Sumter, was the largest Confederate military prison during the American Civil War. The site of the prison is now Andersonville National Historic Site in Andersonville, Georgia. It includes the site of the Civil War prison, the Andersonville National Cemetery, and the National Prisoner of War Museum. 12,913 Union prisoners died there, mostly of diseases. Captain Henry Wirz, commandant, was the only Civil War soldier executed for war crimes.

More info at  en.wikipedia.org