The light plays tricks on your eyes as the red barrels making up the sides of Cristo's first ever installation in the UK seem to be a different colour to their ends. It's not the case. This summer we learn what a mastaba is - a bench, originating in Mesapotamia. The temporary floating scuplture looks more like a decapitated pyramid or iceberg. Take your pick. With it's carefully planned minimal environmental impact is a giant something; part comment on global warming perhaps, part challenging building blocks - grown up lego, part, well, fun.
The best view is across the reeds near the Diana fountain. It grew on me as I walked around the lake, yet I found the pedallos and rowing boats, the typical things floating there, a distraction. I'd rather have seen it alone and colourfully menacing in the water, but that's what happens when you try to introduce art on this scale in the centre of the city. Worth a trot passed, but don't make a special trip.