Chinese (?) coloquialism that's driving me insane

Yes, insane, I tell you!

A few years ago, I was writing some fiction about a Chinese detective, whom I nicknamed ‘The 800’, due to some saying about there being 800 streets (or districts?) in the Chinese capital. Essentially, the saying was analogous to the ‘There are a thousand stories in the naked city’ line. Now, I’m searching for the origin / existence of the saying, and I can’t find it anywhere. Help before I go insane enough that the couch starts talking to me!

Can’t help you - never heard this one but that doesn’t really mean anything. Maybe someone from Beijing can help as it sounds like a localized phrase. And generally speaking, Chinese from outside of Beijing could care less about Beijing colloquialisms.

The more research I’m doing on it, the more I’m thinking it may be something in relation to Judge Di, or Bao Gong An, both Chinese detective fictions. Still can’t find the reference, though… And the couch is starting to murmur.