Since all things I can say have surely been said before, my post is just to reflect my opinion..
first i would be very very careful when using 16mm or 24mm equiv. for portraits unless you want to play with body distortions to make a picture look interesting or funny. The difference how her legs look show this distortion very clearly. perhaps something closer to 20mm (30mm equiv) have had resolved this issue, but better is 50mm (75mm equiv) upwards.
location wise, you stated you wanted to show the mood of this place. the mood may very well be there to the people who have been with you and can remember, but to me from the outside it is very hard to see any story or mood to it. In your position i would have tryed to engage the model into her surroundings, lean on the railings, make her look into the far distance or make her point out the shabby graffities on the wall, something like that.
next is the light, it just does not work for me here. you have a ton of flare in your picture, so that wrong color noise is only partly due to the heavy shadow pull. It would have been better to shoot this picture at f8 or f11 (to mitigate the flare) and work with the on body flash to fill in the shadows.
your models pose does show the limits with your selected focal length, (see above). also, as has been noted before, her pose is not very striking, fear to be photographed often shows in the models pose. you have to clearly state what you want from here and how she must pose. Often i encounter people jeopardize their own photograph, by the way they pose, because they really think of themselves as not photogenic. (Note that i read this only from the photograph, if that is in fact too much interpretation into it and not true, im sincerely sorry and i will remove above statement)
composition is alright i would say, though she as a human being resembles composition wise the pillars to her right and left. a more natural pose that engages her with the environment would greatly aid the picture.
post processing is always down to the tools and skill, I dont know what program you have used. So i cant really comment on it. but as we all like to take pictures i always try to minimize the time i have to spend doctoring with it in front of a screen. So having a well exposed raw file greatly helps. The above suggestions would go in that direction (i.e. f8- f11 / focal length >21mm/fill flash). In photoshop also i would be very careful using clarity slider when having people in the picture, unless you want to bring out bodily flaws on purpose, or having a shaky blurry black and white picture to deal with. You have a lot of wrong color noise in your picture so i would either try countering this with color noise correction or simply bring the picture into b/w. perhaps having the shadows in the picture would also help making it less flat ?=
hope this helps