A Rock Garden ?

Hi Janis, that's what I would call it too, because they planted it rock by rock for a couple of years.
Then someone said it was a New Age structure.
I don't know.

A helix - like the threads of a screw.

I wonder how often one has to water rocks! Maybe those are xeriscape stones.

Thanks for the replies.
The photo is of a front yard in our neighborhood.
If I meet the neighbor, I'll ask about the "rock" garden.

It could be a labyrinth. They are used by some as a symbolic path of a spiritual journey. Pretty cool to have one in a front yard. If that's what it is maybe your neighbor will invite you to use it.

Was the spiral once elevated in the middle, descending gradually? If so, then the idea might have been for horticultural practicality of creating many microenvironments (highly drained & very sunny at the top, increasingly damp as you travel down the helix, sunny on the south, shaded on the north by the structure itself and by the other plants. In this case it has been called an "herb spiral"...I don't think I would care for the maintenance of an elevated spiral, what with gravity acting on it. Clever, though.