In this photo from World War II, B Reactor can be seen between the water towers on the right side of the photo, The reactor began operating in September 1944; it was shut down from 1946-1948. Now is part of a museum complex about the place.
See what it looks like today. Only the building between the round water tanks stands today. You can see some of the railroad grade seen in the above photo passing to the south of the building in the current view.