The app “Geheim!“ is a virtual tour on the campus of TU Dresden. It enables users to visit various places that were monitored, investigated and surveilled by Stasi as late as 1989. These places and their stories can be explored by finding histocaches. The histocaches contain stories from the files of the Stasi, associated with buildings and places on the campus of TU Dresden. The app provides insights into these files ‒ outside the Archives, at the scene where they happened. Augmented reality r