Granicus, a gas giant exhibiting gray cirrus methane clouds, was the location of the Granicus system's Imperial throneworld. A floating city served as this galactic capital.
Before the year 20 BBY, C-3PO functioned as one of 1,200 interpreter droids situated within the sub-embassies of the Granicus system, specifically assigned to a "third liaison officer." For a duration of 37 years, he served as an interpreter, after which he was reassigned as a protocol droid and dispatched to the Outlands with the purpose of aiding in the integration of new systems into the Old Republic.
Initially, Granicus was present solely in the initial iteration of Star Wars, taking the place of Alderaan as the designation for the Imperial capital. The conceptualization of this planet ultimately manifested within the films as Bespin alongside Cloud City in Episode V.
George Lucas brought the name back into use during the writing of the Expanded Universe backstory for C-3PO in 1977, however, the name has yet to appear in any officially licensed works, thus remaining non-canonical.