I added lightening (Xenoflex 2) and rain (Bert Monroy technique) to Piet's retouch
Then added a little to the moody contrast.

Added lights in the windows and edge lighting on building and objects.

forum discussion: http://forums.dpreview.com/forums/read.asp?forum=1006&message=28110533
original image by Shaolin101:

Piet's retouch: