This short article is part of a special issue of the french heritage journal "monumental", dedicated to the "patrimoine de l'enfermement", the "heritage of incarceration". It concludes a chapter, p. 52-78, focusing on the french colonial penitentiary facilities (mainly French Guiana and New Caledonia). It explores how archaeological excavation can help us understand the elements of daily life in the penitentiaries, and also questions the integration of these sites in the local cultural heritage. NB: the downloadable article is an almost finished version, and might contain minor errors.