I cropped the clouds and window closeup out of two different photos, building too. Feathered each photo by 10px. Rotated the building just a bit counterclockwise and added gradient background. Changed levels on the window a little, but otherwise left the colors of the other two photos alone.
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Points for originality, but the soft border makes the overall effect confusing, especially the top two panels. Also, neither the sky nor the window match what we see in the middle panel. It's a very good idea, and I like the individual photos, too.