As other reviewers had pointed out, there is not much to see in this small park. But there is a very strong (and sad) story to tell around the history of the place.
I am sure that there are photos and artifacts that could be displayed along with story boards to tell visitors what happened here during World War 2. This could be housed in a small museum on the grounds. Somebody had also suggested opening up the old tunnels (reinforced for safety of course), so that the visitor gets as close to a first-hand look as he/she can. There is a lot of potential here.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.