Many psychiatric hospitals in Switzerland house a treasure trove of historical photographs that go back to the 19th century and until now have never been studied properly. Glass slides and negatives, loose paper prints, and photo albums allow fascinating insights into the modernisation of these establishments - and at the same time into the history of photography. The medium that was new at the time was used by psychiatrists to record diagnoses, as well as to show the public life behind institutional walls. Thanks to increasingly handy cameras, it was also possible to record the modest celebrations, and leisure and creative activities. Behind Walls introduces these testimonials of life and scientific practice in psychiatric institutions from the late 19th and early 20th centuries that are accessible to the public for the first time. The essays critically study the use of photography as a medium in psychiatry from different perspectives. Text in English and German.