First of all, my apologies for being so late with my reply and thank you all for the effort you put into your interpretations, which show a nice variety of ideas.
There's no interpretation I don't like!
I like the very colorful versions (despite the "available darkness") of Red83152 and deano, which are (a.) for me personally fitting in well with the season in which this picture was taken, as it was spring time then, the most colorful time here in Germany and (b.) the direction I was always had in mind for this exposure. But the topaz-Version and (especially) Bart's black and white version introduce a nice industrial touch. Whereas both of Peter's versions turn the building more into an island of light/surrounded by darkness. Very nice.
So, thanks again.
In closing, here's the result of my own processing at the time: