Hello, here is a little tip which i have recently picked up and thought id share as it makes such a lovely difference.
When working on images of buildings here is how i now add contrast.
Rather then use contrast adjustment layer, i created two levels layers, one darker and one lighter - both with black layer masks.
Now take your time, and paint in, where the face of a building is lighter, make it lighter and the dark side darker. It takes a little time, but certainly gives your image much more depth and a 3D feel to them.
This image has the effect turned off.
The extra layer you can see is a contrast adjustment layer to the lighter layer.
Here is the final image with the contrast technique added.
Subtle but certainly makes a lot of difference to the image.