Walter De Maria, Time/Timeless/No Time (2004). A stepped concrete chamber at Chichu Art Museum, Naoshima: a 2.2m polished granite sphere set on the central stair, the walls ranged with gold-leafed wooden columns, the whole room changing as the daylight moves across it.
Grows from Walter De Maria.
My own encounter, at Chichu Art Museum, Naoshima. No photographs allowed.