The Erich Kästner Museum successfully implements a novel concept: the “mobile interactive micromuseum". It is at one and the same time a work of architecture, a work of art and a utilitarian object and which reflects the multi-faceted personality and work of that world-renowned author, cabaret artist, journalist and man of many other media. With this “walk-in treasure chest”, the architect and originator of the concept Ruairí O’Brien designed, in 1999, a house within a house which combines tradition and modernity and brings together museum content directly accessible to the senses and new media technology. Visitors of every generation and culture can explore Kästner’s world playfully and independently.