Growing up in Warsaw, Poland I had a chance to see many traces of World War II. Some of them are quite obvious, like plaques attached to the buildings all over the city commemorating the many who perished at that particular spot.
But there are a few much bigger artifacts hidden in the forests around Warsaw. These are the remnants of World War II bunkers. So far we have discovered three different bunkers, all on the eastern edge of Warsaw in Mazowiecki Park Krajobrazowy. Unfortunately, I don't know who built them or who destroyed them.