The railings, the angle of the shadows and the perspective on the windows gives the slight impression of a lean even though the building is vertical but I guess my main thing is that I envisaged this as a merging of the shadows with the bough of the second tree in darker tones in B&W. However, when I processed the image to get there the texture of the building resulted in a lack of visual separation and it didn't match what I visualised. It works better in colour. I might try again later but I think I will hit the same problem. Maybe rotating the image a touch clockwise will help as well.