Bornhagen is a municipality located in the district of Eichsfeld within the German state of Thuringia. It serves as the westernmost settlement in the state, although it does not contain the actual westernmost point, which is situated 75 km to the south near Geisa.
The town is situated at the foot of the ruins of Hanstein Castle. Its district, Rimbach, is positioned directly south of the castle citadel at an elevation of 370 meters. Bornhagen is located approximately 22 km south of Göttingen, 85 km northwest of the state capital Erfurt, and 270 km southwest of Berlin.