The Weil is small 50 km long river in Hesse, Germany. It is a left tributary to the Lahn river and the city of Weilburg is located next to its mouth. The river flows exclusively through the Taunus mountain range with its source being located between the Kleiner Feldberg and Großer Feldberg mountains. It flows through Schmitten, Weilrod and Weilmünster.