I’m in Xi’an, the capital of Shaanxi province (not Shanxi province, which is different as you may recall.) It was also the capital of many dynasties all the way back to the Qin, although under many different names.
The current name 西安 means “Western peace” but that might have something to do with promise of the 40 foot tall rectangular wall all the way around the heart of the city. And the wall is even thicker than it is tall.
The Chinese have a wall fetish.