abstract architectural backdrop background barrier brick brick-wall bricks brickwork cement coloring colors colouring colours constructed exterior external firm linear lines mortar perspective perspectives rectangular secure security smooth solid standard strength strong style surface surfaced surfaces texture textured textures traditional-brick-wall variation varied various wall walled wallpaper well-built alcove angles corner dirty grime weathered cemented concrete limestone local-stone old pattern patterns random randomly-coursed retaining-wall rock rocks rough rural shape shapes significant stone stone-walled stones stonework stucco traditional uneven variations variety