The Castle Mill ("Schlossmühle") lies at Heidesheim's southwest edge at the foot of the cadastral area of Sommerau. There Sir Werner of Winterau owned land that he bequeathed to his sons in his will of 16 August 1317. Ernst Krebs has presumed that on the Castle Mill's lands was a farm whose land was already being worked by Sir Werner's forebear Herdegen II. That he moved from there to the castle in 1209 does not make sense – on 27 October 1577, Hans Georg von Bicken (d. 1608) sold Heinrich von Stockheim (d. 1588) the Castle Mill area. Hans Georg von Bicken, from the family Bicken, was the Electoral Mainz vicegerent ("Vitztum") in the Rheingau and "Vogt" of the Mainz Convent of Altmünster in Heidesheim; Heinrich von Stockheim was cathedral cantor at Mainz, povost of Saint Alban's Abbey there and Electoral "Amtmann" in Heidesheim.