PurposeThis paper has two purposes. One is to examine the ways mentally disabled children were disciplined and cared for in Berlin, Germany/Prussia, at the end of the 19th century, by considering the way the architecture of the asylum affected the practices within it. The second purpose is to examine the manner in which the practices at the Dalldorf Asylum, especially the administrative paperwork, fabricated and stabilized the medico-pedagogical category of “feeble-mindedness”.Design/methodology/approachThis paper engages with reflections on asylum architecture and its connection to disciplining bodies as shown in Disability History and linking these insights to recent scholarship from the field of Science and Technology Studies on the fabrication of knowledge through observation. Drawing on microhistory as methodology it examines the fabrication of “feeble-mindedness” with and within the Dalldorf Asylum, focusing on architecture and design as well as administrative practices.FindingsThe analysis of the asylum's architecture reveals how certain ideas of hygiene and control derived from 19th century psychiatry, along with personal attentiveness and individualized learning were incorporated into the building, creating the notion of a “feeble-minded child” as being simultaneously dangerous and in danger. The paper further shows how the professionals involved were struggling with diagnosing these children, further showcasing that the space as well as the categorization of children, oscillating between psychiatry and pedagogy, has to be understood as contested.Originality/valueThis paper engages findings on the disciplining structures organizing everyday life within the asylum with concepts of fabricating knowledge as central to science studies. The Dalldorf Asylum, the earliest state-funded asylum for mentally disabled children in Germany and largely understudied, is used as the main research object. A microhistorical approach allows to make visible the intricate yet mundane practices involved in stabilizing the category of “feeble-mindedness”.