Fundametal point of
the geodetic network Deutschen Hauptdreiecksnetzes (DHDN) and its
coordinate reference system on the Bessel-ellipsoid of Germany.
It was used since 1832, and was destroyed in 1910. Since then, the Helmertturm in
its role as fundamental point, but it got only calculated coordinates.
At Rauenberg, since 1985 there exists a monument.