20.02.2012 
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 
Potsdam got 
its role as fundamental point, but it got only calculated coordinates.
At Rauenberg, since 1985 there exists a monument.