Abstract: A cornice for a construction work having an upright surface has a plurality of similar elongated panels of like section and predetermined length. These panels are laterally concave and each have a pair of parallel longitudinal edges and opposite longitudinal ends. A plurality of respective mounts each generally complementary to the concave section of the panels are anchored on the surface spaced apart by a distance equal to the length of the panels. Interengaging formations on the mounts and on the edges of the panels allow the panel edges to be hooked to the mounts. A tensioning device secures the respective panel snugly to the respective mount. Each mount comprises an outer mount member of a convex shape complementary to the concave section of the panels and an inner bracket fixed on the outer member. The anchoring device is secured to the inner bracket.