It is in the Bavarian Alpine Foreland. The town stretches from the shores of the Ammersee to the forested morainic hills of the Saale and Würm glaciation.
The town area consists of the market town of Dießen (with St. Georgen, Wengen, Ziegelstadel, Bischofsried and Seehof) and the former independent boroughs of Rieden (with Riederau, Bierdorf, Lachen, St. Alban and Romenthal), Dettenschwang (with Oberhausen, Unterhausen, Wolfgrub and Abtsried), Dettenhofen (with Pitzeshofen, Engenried, Hübschenried and Ummenhausen) and Obermühlhausen (with Oberbeuern, Unterbeuern and Schlöglhof).[3]
Sources
Weißhaar-Kiem, Heide (2010). Landkreis Landsberg am Lech. Landsberg am Lech: Landkreis Landsberg am Lech. pp. 170–179.
Schnurer O.P., M. Aquinata (1976). Heimatbuch des Marktes Dießen a. Ammersee. Diessen: Markt Dießen a. Ammersee. pp. 19–231.
Hugo, Josef Anto (1901). Chronik des Marktes und der Pfarrei Diessen. Diessen: Markt Dießen a. Ammersee. pp. 41–68.
Fried, Pankraz (1991). Aus Schwaben und Altbayern. München. pp. 122–124.{{cite book}}: CS1 maint: location missing publisher (link)
Schweizer, Bruno (1999). Das Dießener Heimatbüchlein. Dießen am Ammersee. pp. 4–48.{{cite book}}: CS1 maint: location missing publisher (link)