Wow! was my first impression when I first saw this image. So it is pretty obvious that I like this photo.
First of all, it is very symmetrical so you have easily met the challenge. I really like the two torches or sconces that raise up at the top as well as the flow of the arch into a point at top center. You chose a very good perspective to show the symmetry here. I'm having a hard time deciding if I would like to see more of the door or if it just right the way it is. It is hard to know without seeing other views. I just purchased a wide angle conversion lens and I am really loving the wider angle shots. Of course it is very dependent on the subject.
Clearly the other element in this photo is the beautiful textures and features of this old building. While it is good as it is I think it could have been improved by more contrast with more direct lighting. This would make an excellent subject for studying the effects of various lighting situations.
The color and values appear very natural except I don't like the bluish sky reflecting in the door. A little hard to avoid, I know. Maybe you could have desaturated some of the blue and cyan channels since blue is not a prominant color in this image.
Technically everything looks pretty good and your depth of field is appropriate for showing all of the details clearly.