Aiming both at an ethnography of expertise and at a sociology of values, this paper describes a meeting of the “commission régionale de protection du patrimoine et des sites” (local commission in charge of protecting national heritage), discussing the options between the “classement” (classifying) or the “inscription” procedures of a building on the list of historical monuments. After having thoroughly reported the discussions between experts, the paper brings out the criteria, values and value registers used when dealing with national heritage. It thus puts forward the effective and complex links between the values of ancientness, rarity, beauty and, moreover, authenticity.