The Alashan city control center was the central structure within the underground city of Alashan. The structure was the source of power for the entire city, and any damage to its internal workings adversely affected the technological systems of the city. As well as providing general power, the control center was the source of power behind the Guardian of Forever which protected the entire city.
Around 0 ABY, the Rebel heroes, Luke Skywalker and Leia Organa infiltrated the control center and critically damaged it, shutting down power to the enormous city and killing the Guardian of Forever. However, after the Rebels had left the planet behind, the power in the gigantic complex started back up, implying that the complex had found some way to repair itself.