In the 18th century, a changing view on criminal law and the custodial sentence gave rise to the new architectural typology of the cellular prison. This typology became widespread in the western world during the 19th century. In Belgium, between 1844 and 1919 a network of almost thirty cellular prisons with a star-shaped structure of cell wings converging in a central observation point was built, based on the Anglo-Saxon model. This building campaign, urged by first General Inspector of prisons Édouard Ducpétiaux, had granted the country a solid international penitentiary reputation. Prison historiography’s unilateral focus on Ducpétiaux’ efforts however, has relegated the architects who designed and built these ‘Ducpétiaux-prisons’ to the sidelines of architectural history. In order to disclose their contribution to the development of the cellular typology, the aim of the PhD project is twofold. First, it identifies all actors involved in the design of the cellular prison by analyzing the prison building discourse within the context of 19th-century Belgium; second, it assesses these actors within the institutional framework of the building campaign as administered by the Ministry of Justice.