The Dairy in the New Garden was built to plans by the master builder, Carl Gotthard Langhans, on the shore of the Jungfernsee lake at the northernmost tip of the New Garden in Potsdam, Germany. Construction was carried out from 1790 to 1792 by Andreas Ludwig Krüger.In the course of laying out the landscape garden and building the Marble Palace under Frederick William II of Prussia, a dairy was built to supply the royal court. Cows grazing on the surrounding land produced milk for the manufacture of butter and cheese.
In 1843/1844 Frederick William IV. had the building extended. To a design by the architect Ludwig Persius a second storey was added under the direction of Ludwig Ferdinand Hesse and the southwest corner was enhanced with a tower. Battlements run along the edges of the roof and give the building a Norman character.
Wikipedia https://en.wikipedia.org/wiki/Dairy_in_the_New_Garden
Coordinates 52°25'19.367" N 13°4'10.948" E