I think that you have a nice vertical symmetry here. I don't think that all symmetry photo's need to be in landscape mode. I like your subject matter as well. You do suffer from having to take the photo from street level which introduces some interesting angles, but it's not enough to lessen the impact of your shot. I think that boosting the contrast would assist this photo. As it stands now, it's kind of flat. Cropping could be a little tighter. The building has natural crop points and if you used the bottom and top window lines, still including the building on the left, I think you'd have a stronger composition.
Your post processing is good, no artifacts from compression or resize.
I like this image, I would like to see a reshoot with the sun lower in the sky so as to introduce some more interesting colors and shadows.
This photo needs more contrast for sure. I'm not really seeing the symmetry part either. If it were supposed to be the windows, I'd have cropped off the side of the building on the left.
I don't really get symmetry from this, but the photo does have a good balance, and a pleasing composition. The colors are all soft and muted, and while I find it to be a nice photo, it lacks real impact for me.