The photograph in the background shows the prisoners lined up along the concrete ditch in front of the electric barbed wire fence on the west side of the main Dachau camp. The barbed wire fence is out of camera range on the left hand side. At the end of the row of wooden barracks is the camp greenhouse which was located where the Protestant Memorial church now stands. This photo was probably taken from the top of Guard Tower B. Notice the American flag on the top of one of the buildings obtained from:

https://zenit.org/articles/70-years-after-dachau-a-concentration-camp-for-jews-and-priests/