Space under stairs outside can be utilized to be various of things. Most often, this corner void is ignored, left with usual white paint. Exposed with heat and rain in a long time, it will be dull and rumpled if not being cared well. This time, I'll use it as my cactus sanctuary. To spice things up, I add mural paintings with desert theme to brighten it up. The bright color can be used to cover the possible growing-moss too.