
Originally Posted by
Mike Buckley
I think the sky complements the structure in this case by being totally black. Try it to determine if you like it.
If you do decide to add some light to the sky, make sure the direction of the direct light is consistent with the direction of the reflected light. The reflected light on the buildings seems to be coming mostly from the left, whereas the direct light that you added to the sky is coming from the rear.
For other ideas, review the photos Ansel Adams made with a dark sky. Some of them are totally black except for the brighter light that appears as a gradient near the horizon.