This is the original real-deal City State of the Invincible Overlord! This is the most awesome & storied metropolis in gaming history.
However, there is more CSIO street info you need in Initial Guidelines Booklet I. You also need a map, and DriveThru RPG only sells a PDF of the player's map to the city state.
Note also that Initial Guidelines Booklet J is not available, and that contains information about Thunderhold and Sunstone Caverns, both about 100 miles to the north above city state.
So, whomever is handling Judges Guild, please see if we can get Initial Guidelines Book J and a single copy of a judge's map for City State. That would be awesome historical goodness!