The story: https://fridayeveryday.com/forbidden-city-cats-become-celebrities-in-their-own-right/
Some are descended from the cats in the royal palace of the Qing dynasty, and since then until now, the Forbidden Palace has been free of rats (for hundreds of years!).
Photo credit: From the above link.
The cats keep the Forbidden City clean: https://www.bbc.com/news/blogs-news-from-elsewhere-26366744