International audienceThis paper focuses on reviewing the monumentality associated with Neolithic megaliths in western France, in all its diversity. This region cannot claim to encompass the most megaliths in Europe, but it is, on the other hand, one of the rare regions where mega-liths were built recurrently for nearly three millennia, by very different human groups. We will first of all define the terms of the debate by explaining what we mean by the words monuments and meg-aliths and what they imply for the corresponding past societies in terms of materiality, conception of space, time and rhythms. The notion of the architectural project is central to this debate and it will be presented for each stage of this very long sequence. This wi...