This spring we installed a crevice garden with granite flagstone laid on end into the earth to look like an outcropping of fissured bedrock.
Looking up from the sidewalk the strong diagonal rhythmn created by laying the stones this way stabilizes the look of the property's challengingly steep grade.
I really like building these types of 'imbedded' retaining walls (which is basically a kind of 'pitching' or cobbling ) as an alternative to the usual upright 'stepped' terracing.
The hill is easier to walk up and down and also provides a level walking area immediately above the wall making it possible to stand and cut the grass above. This kind of 'wall' still holds back the earth and prevents erosion.
Next year, when all the alpine plants, mosses and small flowering plants have taken root in the crevices, this slanted garden rockery wall will look stunning.