Well, no; I did mean your image (which you gave the caption "GX100"
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Well, there are several details, not all of them easy to verbalize (why is Alfred Stiglitz´ "The Steerage" a major masterpiece?).
First, the obvious surprise effects, like people walking around above the water in a not entirely obvious topology, and the unexpected dome of St Paul´s exactly above the bridge pillar. Then the entirely different colour keys in the upper and lower parts, and the careful balance between the heavy pillar-dome structure and the main figures on the bridge.
All these elements contribute to a puzzling mixture of disconnectedness and unity, in a very complex image, and thus one tends to remain with the image and try to sort out what exactly is going on in there. Obviously, all this is subjective, but I find I have to look far longer at this image than at the superficially similar, but far simpler, escalator image directly below it.