Once you've decided on materials, think about any details you'd like to add, for aesthetic or practical purposes. Color could be added to some or all of the wall, depending on the material. Masonry walls benefit from capping or coping to frame the top of the wall and allow water to run off. Planting in crevices is another possibility, as in these pockets of soil at the top or on the face of a wall. Limited water will be available to them, however, so choose species that can flourish in dry conditions.