The claim: Northeast area of Anchorage - far end of base. Garden Plot facility.
What it really is: It's an Air Force base within Anchorage that was built right before World War Two.
The base itself is pretty compact for an Air Force base, but still, none of the buildings look like something from a prison camp, and actually look like what you would find on a typical Air Force base.
Also, it would be pretty hard to hide prison camp around a city as large as Anchorage.