The finished image below was a hard one to process as the original photo was taken with my normal P&S digital camera and the details captured were very limited. For example the strong light glare on the reflection could not be edited.
As you will see, the sky was a separate image, so I simply cut out the buildings and played them on a different layer above the sky image. The processing was also quite eay to do, just convert to greyscale and then play around with the hues, contrast and a bit of dodge & burning on the sky! Voila! :)