 Weimar is situated within the valley of Ilm river, a tributary of Saale river on the southern border of the Thuringian Basin, a fertile agricultural area between the Harz mountains in the north and the Thuringian Forest in the southwest.The municipal terrain is hilly; the height of the city centre in Ilm valley is approximately 200 m of elevation.To the north, the terrain rises to Ettersberg, the city's backyard mountain, 482 m in height.