In the randform post Heiligensee I hypothesized that an ancient oral tradition from the village of Heiligensee might indicate that cults of the germanic goddess Nerthus could have taken place there. I am fully aware that this is super speculative and in particular that it is outrageously unlikely that there is an oral tradition in Berlin which is 1500-to 4000 years old (thats approx. when the semnones lived there). It would not be too far fetched to assume that the tales of Nerthus were converted into tales matching the surroundings of Heiligensee. Nevertheless it should be reminded of that there are oral traditions which lastet for rather long time like the vedas (with by the way interesting error correcting schemes).
Anyways for me the the oral tradition was so compelling close to the Nerthus tales and to the fact that there might have been an ancient sacred location that I was motivated enough to travel to the other side of Berlin and to look for something like a sacred grove, a thing location on a raised mound and/or even a tumulus like in Old Uppsala. That is I looked at the hills across from Sandhauserstr.99 which are called Schifferberge. It should be said that in this area dune hills are rather common, so that when I started out I was quite convinced that the option tumulus was rather a joke. That is I was convinced that the Schifferberge are just dunes instead of containing a tumulus, but I am not so sure anmore. But see the images.