Eisenach is a town in Thuringia, Germany with 42,000 inhabitants, located 50 kilometres west of Erfurt, 70 km southeast of Kassel and 150 km …Eisenach is a town in Thuringia, Germany with 42,000 inhabitants, located 50 kilometres west of Erfurt, 70 km southeast of Kassel and 150 km northeast of Frankfurt. It is the main urban centre of western Thuringia and bordering northeastern Hessian regions, situated near the former Inner German border. A major attraction is Wartburg castle, which has been a UNESCO World Heritage Site since 1999.