abstract architectural architecture background barrier basic brick brick-wall bricks color colors colour colours crack cracked cracks damage damaged danger deterioration exterior external garden lean leaning retaining-wall solid split-levels splitting standard strained strength surface surfaces texture textured textures uneven wall appearances arid Cacti cactus clumps clusters coloring colouring display edge edges flora garden-display garden-plants irregular leaves light ornamental perennials plants pointed protection shape shapes sharp short-spikes small-spines spikes spines spiny succulents unusual