The Erich Kästner Museum has successfully implemented a new type of museum concept. The "mobile interactive micromuseum" is a piece of architecture, a work of art in itself and an everyday object that reflects the multifaceted personality and work of the world-famous author, cabaret artist, journalist and media personality Erich Kästner. In 1999, architect Ruairí OʼBrien designed the "walk-in treasure chest", a house-within-a-house that combines tradition and modernity and hands-on museum content with media technology. Visitors of all generations and cultures can playfully and independently explore the complex world of Kästner.