A great shot. I am not sure if I have worked it out correctly but here's what I think it is. It's a painting on a blank grey/ white wall of 4 men and railings so they appear to be walking in mid air and there is genuine depth in the background
Is that correct? It's very effective illusion - almost surreal. The painting is so good, at least on a photograph that it is almost as if there are real men just walking pas the woman and the dog