Alpha Centauri City was a city.
Phil Bishop Raymond was born there in the 22nd century. (TNG-R: "The Neutral Zone", okudagram)
Peter Molnar Raymond was born there in the 23rd century. (TNG-R: "The Neutral Zone", okudagram)
The city name only appeared in the remastered version of Clare Raymond's family tree. Presumably, it is located in the Alpha Centauri system.