For example, while following a lead about a couple Tennessee men who were taken to an Alabama prison during the time of the Civil War, I discovered Cahaba Prison. Cahaba Prison, also known as Castle Morgan, is located in Old Cahawba, Alabama (I'm not sure why there is a spelling difference). It had been an unfinished cotton warehouse that the Confederate government turned into a prison. Although there were only 432 bunks, it would eventually house more than 3,000 men by 1865. A staggering number crammed into a small space. You can imagine that the living and hygiene conditions were horrendous. Surprisingly the death rate was only 2%, which compared to other prisons this was very low.
There is also an archaeological site in Old Cahawba, which incidentally is where Alabama's first state capitol was built. After massive flooding in 1865 the county seat was moved to nearby Selma. Today you can visit Old Cahawba and the various surviving buildings of this ghost town. There are guided tours for a fee or self guided tours available.