The first thirty years of the French conquest of Algeria witnessed the large-scale destruction of Algiers’s cultural heritage. Researching the processes by which this came about leads us to consider the conditions of production of two sources that refer to the period before the conquest: Les édifices religieux de l’ancien Alger (The Religious Edifices of Old Algiers), by Albert Devoulx, and the “Ottoman collection” of archives initially established by the same figure. This dual archaeology, based on the reconstitution of Devoulx’s activities during his lifetime, reveals a virulent struggle over civic rights and particularly over the appropriation of endowments established by the city’s religious institutions. The sources considered here were part and parcel of this struggle. By paying attention to the claims they set out and the interactions between them, it becomes possible to retrace the disappearance of the mosques of Algiers and to appreciate the true nature of these sources.