[Archelaos]

"Burgstall" is not a place name, but technical terminology for a location of a former castle of which almost nothing is left. See: https://de.wikipedia.org/wiki/Burgstall

In the case at issue here, the rock was called "Burgstein" and the forest around it "Burgholz". This names were already mentioned in a book from the 15th century and a book from the late 16th mentions a castle at the "Burgstein".[1] All this was long known,[2] but not all experts were convinced, that there had indeed been a castle on the rock. The new excavation now makes it seem even more likely.

[1] https://www.unsere-burgen.de/de/Burgen-im-LK-Reutlingen/Burg...

[2] For example, one Gottlieb Fri[e]drich Rösler wrote in his "Beiträge zur Naturgeschichte des Herzogthums Wirtemberg" (2. Heft, publ. 1790): "Auf dem Burgstein einem grossen Felsen gegen Abend, auf dem die Aussicht nocht schöner ist, sind auch die Spuren der alten Burg unkenntlich geworden ..." ("On the Burgstein, a large rock towards the Evening [the West], where the view is still more beautiful, even the traces of the old castle have become unrecognisable ..."). See p. 81 of: https://books.google.de/books?id=BY05AAAAcAAJ&printsec=front...