The concept of heritage includes at present a multitude of items, items which are intended to be transmitted from generation to generation, by the fact that we associate to them one or several values, the variation of these values through time controls our behavior towards these items, and it is with the intention of transmitting them that these items are conserved, preserved and restored.
In this field, religious heritage is a special category; beside the other values which can be associated to it, its association with the divine confers to it a high sacredness ; That can explain the uses of this sort of heritage while the conflicts between communities.
The conversion of mosques or churches is a way of taking this heritage by a community from another one; this act, its motivations, its progress and its reception inform us about the relation between society and his heritage, and clarify the transmission process.
Conversion occurs in particular political, religious and social contexts. It requires a specific approach in every case; this is why this paper studies the case the mosque/church Ketchaoua in Algiers, in order to analyze actions during the various conversions of this building and understand the transmission of this monument.