The Museum of East Alabama includes an exhibit on Camp Opelika:
Interesting camp equipment, such as the guard tower spotlight ... and the last remaining barracks building
The Encyclopedia of Alabama has a great article on POW camps in the state:
During World War II, the state of Alabama was home to approximately 16,000 German prisoners of war (POWs) in 24 camps.
The Army Corps of Engineers constructed Alabama's first camps during the winter of 1942-1943. Army doctrine dictated that camps be built either at existing military bases or at sites distant from major cities and industrial centers, and military surveyors toured the state for suitable locations.
Camp Opelika was capable of housing 3,000 POWs
(There's lots more in the article.)