What do you need when running a city-based campaign? Some things are:
- Lots of roughly detailed locations and NPCs.
- Lots of rumours.
Number - Name
Secret: something which could be very interesting to adventurers, but which is not commonly known.
Hook: a direct adventure hook which can be found at this location or via this NPC.
Connection: at least one connection to another numbered entry.
So the same collection of numbered entries can both be placed on a map as locations, and used as random rolls for rumours and adventure hooks.