Hill
this is very similar to concept B, except we'd use degenerated granite instead of mulch, and we can re-use the flagstone so the lines will not be as defined. But re-setting the flagstone could be similar in cost to pouring new concrete. they also used corten steel planters and concrete walls here too.
we could do pour in place large steppers like this with gaps if we went the concrete route vs the flagstone
Q