Most of these walls were done with old lava stones that were at a house retaining the land in a very informal way and we rolled them out and cleaned off all the dirt, Digging back a ways and reworked the rocks into a formal wall.  In the case of the wall on the sidewalk, we used an advanced drain system for durability and structural strength.  Using a filter cloth up against the soil, laying the perforated drain pipe in the bottom of the trench, back filling with pea gravel, and providing weep holes every twenty feet.
Once near the top,  six inches to a foot,  fold the filter cloth over the pea gravel and top dress with a nice blend of soil.