- "Fear. A Jedi spends his whole life training against it. But at the Citadel, breaking Jedi is our specialty. Within these walls, they will learn to fear us. And if not, they die."
- ―Osi Sobeck
- "The Citadel wasn't designed to hold common criminals, it was created to hold Jedi if any of us lost our way."
- ―Anakin Skywalker
Built five hundred years before the Clone Wars, the Citadel was originally designed by the Galactic Republic to hold rogue Jedi. During the Clone Wars, it fell under control of the Confederacy of Independent Systems, which conquered Lola Sayu early in the war. It was run by warden Osi Sobeck, who was considered to be sadistic. The Jedi Archives was known to have information on the original layout of the facility, but this was considered extremely old and outdated by the time of the Clone Wars.
Under Separatist control, the Citadel became known as the Confederacy's most isolated holding facility. The prison was heavily guarded by a number of droids including droid commandos and hundreds of electro-mines. The clone trooper training facilities in Tipoca City on Kamino used a training course simulating an attack on the Citadel as part of their programs. During their trials, Domino Squad succeeded in completing the course.
At one point, Jedi General Even Piell was captured, incarcerated and tortured for information regarding the Nexus Route in the Citadel prison, prompting an elite rescue team led by Jedi Generals Obi-Wan Kenobi and Anakin Skywalker to free him. Osi Sobeck was killed by Ahsoka Tano when he prepared to throw Captain Tarkin into the lava gorge as a last-ditch effort to keep the Republic from gaining information on the Route. Although Tarkin lived, along with the Nexus Route information, Piell was killed by an Anooba, but not before giving Ahsoka his half of the information.
- Star Wars: The Clone Wars – "Clone Cadets" (First mentioned) (Indirect mention only)
- Star Wars: The Clone Wars – "The Citadel" (First appearance)
- Star Wars: The Clone Wars – "Counterattack"
- Star Wars: The Clone Wars – "Citadel Rescue"
- (First identified as Citadel)
- Star Wars Character Encyclopedia (First identified as Citadel Station)
- "Season Four Secrets"—Star Wars Insider 128
- Star Wars: The Clone Wars: The Complete Season Three
- Star Wars: The Ultimate Visual Guide: Updated and Expanded