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.Karl Rossel, Hrsg., Urkundenbuch der Abtei Eberbach, Bd. 2, Wiesbaden 1870, S. 665 Nr. 793. 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 senseErnst Krebs, Zur Geschichte von Heidesheim, in: Männer-Gesang-Verein Einigkeit Heidesheim, Hrsg., Festschrift zur Fahnenweihe verbunden mit Wertungssingen am 4., 5. und 6. Juli 1925, Gau-Algesheim o.J. (1925) S. 5-33 bes. S. 25. – on 27 October 1577, Hans Georg von Bicken (d. 1608) sold Heinrich von Stockheim (d. 1588) the Castle Mill area.Hessisches Staatsarchiv Darmstadt, Bestand A 2 Nr. 84/42. 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.
