The Castell system existed as a star system situated in the Colonies area of the galaxy. A planet revolved around the system, and in its turn, was circled by the Orbital Shipyard CC-24 belonging to Sienar Fleet Systems. In the days of the Galactic Empire, a group of thieves under the command of smuggler Lando Calrissian absconded with the personal pleasure yacht of the Galactic Emperor Sheev Palpatine, named the Imperialis, from CC-24. Three Star Destroyers were dispatched to reclaim the yacht before it could flee, and to obliterate the shipyard as a consequence for permitting the theft. The Imperials managed to demolish CC-24, but were unable to prevent the Imperialis from getting away.