Rheinsberg Palace lies in the municipality of Rheinsberg, about 100 kilometres northwest of Berlin in the German district of Ostprignitz-Ruppin.
The palace on the eastern shore of the Grienericksee is a classic example of the so-called Frederician Rococo architecture style and served as a basis for Sanssouci Palace.
Wikipedia https://en.wikipedia.org/wiki/Rheinsberg_Palace
Coordinates 53°5'54.223" N 12°53'23.272" E