Gnarcissus

You're gonna wanna start on a couple of decent lips with good feet. You'll move up right (or left) to a pretty similar lip. Then you'll find another one up to the left (or right). Keep doing that!

Walk to the bottom of the tallest part of the retaining wall and start climbing!

Bring some webbing etc. long enough to get the rope over the lip of the wall, so it's not rubbing against it.