Coruscant (from Star Wars I - III, VI)
Coruscant, an ecumenopolis, was renamed Imperial Center during the reign of the Galactic Empire. The adjective form of the planet name is Coruscanti. Coruscant was the capital of the Old Republic, the Galactic Empire, the New Republic, the Yuuzhan Vong Empire and the Galactic Alliance at various times.
Coruscant is the actual center of the galaxy, given that its hyperspace coordinates are (0,0,0).