The castle of Schönburg stands in the park Gesundbrunnen, which stretches on the northeast edge of the centre of Hofgeismar. It is located at about 150 m above NHN on an artificially piled hill. About 50 m south of the castle lies the Swan Pond. Not far to the east, around the eastern border of the park is the Lempe river, which flows a few hundred meters further west into the south-coming Esse river.
The castle was built from 1787 to 1790 according to plans by Simon Louis du Ry for the Landgrave Wilhelm IX.