The old town of Pingyao, with it's city walls intact, would have been very impressive - if it hadn't been so polluted.
Our guidebook (published in 2004) claims that this small town has escaped the development of much of the rest of China. Obviously, in the past few years, the race to develop has begun. Old parts of town are being knocked down. New buildings are being erected. And, a thick smog of coal dust and desert sands sits over the whole city.
We spent several hours walking (and biking) around the walls, but the whole experience was marked by the sights, sounds and smells of "development."