The Slovenian Museum of recent history in Celje creates in an international cooperation the first European exhibition about the history of operetta and the musical entertainment theatre. The focus is not as customary on the demonstration of visible and hearable products of this European cultural heritage, but on the different moments of creation in various social, cultural and historical context. 2 towns in middle Europe bring together their stories of operetta, also with the help of contemporary whitnesses. Bad Ischl in Austria, a former living place of many composers and since 50 years the location for the Lehár Festival, thereby plays a main role. In Eggenfelden in Germany almost 50 years ago an own operetta theatre was founded by the initiative of some citizens. A very young operetta theatre in Warschau carries in modern conceptions and experiences from the east of Europe.The interactive exhibition is made especially for young people but as well as for men of all ages. It shows10 stations: ouverture, the rooms of motivs, creation and realisation, design, production, rehersal, performance, response, the eternal circle and finally the room of JUMUM about the new creation of musical theatre. Parallel with the openings of the exhibition in Austria, Germany and Slovenia take place the first JUMUM-Festivals: Young composers from the partner countries have created in a master class with one of Austria's leading composers new scores for short pieces of musical theatre. In their countries teams of young artists put the scores on stage and present them during the Festivals. The experiences of the new musical theatre performances and of old and new stories of operetta-creating in the exhibition enrich each other. After their presentation in an European conference of museology in Eggenfelden the exhibition will stay permanently in Celje, continously being enriched by new "stories" from the ongoing European JUMUM-network of new festivals and cooperation projects.