Achern is a city in Western Baden-Württemberg, Germany. It is located approximately 18 km southwest of Baden-Baden and 19 km northeas…Achern is a city in Western Baden-Württemberg, Germany. It is located approximately 18 km southwest of Baden-Baden and 19 km northeast of Offenburg. Achern is the fourth largest town in the district of Ortenau, after Offenburg, Lahr / Black Forest and Kehl.