Wiesbaden is located in west central Germany at the southern foot of the Taunus Mountains, on the Rhine River, near Frankfurt. It is popular for its 26 hot mineral springs and mild climate and tourism is vital to the local economy. Wiesbaden is a cultural center; places of interest are the former royal and ducal residences; the Kurhaus with its casino and its concert halls; the Colonnade, remnants of a Roman wall known as the Heidenmauer ("heathens' wall"); and the Hessian State Theater.