My garden is steeply terraced, and the bottom retaining wall is an ugly concrete block affair. My guess is that it was always meant to be finished, but never quite got there. That long-term ambition to green that wall up (unlike household walls, moisture on this wall will be no problem) is curtailed by the lack of light in that tiny space. It'll need to be grotto planting; very tolerant of low light indeed.
This sunny bank out beside a Boathouse's floating wharf on the Thames has the look I like though - semi-wild, space for the stones between the plants. But I suspect I'll have to swap around species -- Asplenium for the Hart's Tongue, maybe. And should I be putting a loose stone face on the concrete for the plants to peek out of?
I think about it on the way home, past the distractions of June. The house on the corner of my street has old fashioned climbing roses threaded through mature apple trees. The roses are small and apple blossom pink and highly scented, so it raises your head to the flowers as you walk by.