Abstract: A wall facing system including elongate wall facing tiles (15) of stone material and mounting bars (11) adapted to be secured in a vertical position on a building wall to support the tiles (15) with the tiles positioned one above the other and having their longitudinal dimension horizontal, and with vertically adjacent tiles adjacent and, optionally, overlapping one another. Each facing tile (15) has on its front side a rebate (15A), which extends along the upper edge of the tile, and a front plate, which extends from the rebate down to the lower edge of the tile. Moreover, each facing tile (15) has on its rear side a downwardly projecting support rib (15E), which extends in parallel with the upper and lower edges of the tile.