The Fils is a river in Baden-Württemberg, Germany, a right tributary of the Neckar. Its source is in the Swabian Alb hills near Wiesensteig. It flows through Geislingen (Steige) and Göppingen to join the Neckar east of Stuttgart, in Plochingen. Due to the contribution of the Fils, the Neckar is navigable from there. Geography Course The Fils has its source on the Swabian Alb about two kilometers southwest of the town Wiesensteig. Its karst spring, the Filsursprung, lies at 624.9 m in the Hasental valley, which has remained close to nature. There are two more springs a little further down, the Kleiner Filsursprung on the right and the Hasenquelle on the left at the foot of the slope. The young river - initially running in a north-easterly direction - crosses the community Mühlhausen im Täle after Wiesensteig, where the Hollbach flows on the left side and the Bundesautobahn 8 crosses the valley. Then follows Gosbach with the mouth of the Gos on the right side. In Bad Ditzenbach the Hartel flows into the river from the left and the Ditz from the right. In Deggingen the longer Schinderbach flows into the Fils from the left and the short waters Sennenbach and Schüttebach from the right. At Reichenbach im Täle in its lowest valley the Fischbach and in Hausen an der Fils the Rohrbach flows into the Fils. In Bad Überkingen the Rötelbach coming from the right lets the Fils grow further. Through Geislingen an der Steige, the Filstal describes a 90 degree left turn, where the Eyb (river), which flows in from the northeast, joins in. The Eyb is the first longer and on the surface also more catchment area-rich tributary from the right side, after the streams running in from the left from the crumbling inner side of the Alb Eaves have so far regularly exceeded their counterparts on the edge of the flat Alb plateau in both characteristics. The Eyb river absorbs a northwestern tributary from Amstetten before its mouth, which is why Geislingen lies in a wide valley spider. From now on, the Fils also runs in a northwesterly direction through its outlet bay from the Alb into the Swabian Keuper-Lias Plains, where Kuchen and then at the tributary of the Marrbach Gingen lie. In the meantime, before the Alb, the right Lauter, the largest tributary of the Fils at all, flows into Süßen on its last