The Betan city was a city settlement of the Betan civilization, name unspecified, on the planet Beta III in the C-111 star system in treaty boundary quadrant 1 in the galaxy's Alpha Quadrant. (TOS episode & Star Trek 9 novelization: The Return of the Archons)
- In TOS remastered, the aerial view of the planet showed only sparse signs of settlement, indicating the stagnant culture might only have been centered around one population area in this city. Presumably, that would be why the USS Enterprise landing party chose this venue for observation, but it also could have been one of a number of settlements, making it more of a coincidence that the Starfleet visitors picked the one where the Landru computer was situated.