The Heroes' Organ was set up on the top floor of the Burgers' Tower (Bürgerturm} in 1931, to commemorate the German and Austrian dead of the First World War. Its daily recitals can be heard for several miles around, in still weather, at midday and at 6 p.m. from the beginning of June until mid-September. This is undoubtedly the largest outdoor organ in the world, with 4 307 pipes and 46 registers. The keyboard and auditorium are set up at the foot of the rock.