The Spire, also known as Stygeon Prison, was a clandestine and isolated prison fortress integrated into the mountains of the planet Stygeon Prime. Its origins and the identity of its builder remain a mystery, and it was constructed using exceptionally durable transparisteel. During the Clone Wars, the Confederacy of Independent Systems secretly utilized it, and later, during the Imperial Era, it was employed by the Galactic Empire and their Inquisitorius.
During the Clone Wars, the Confederacy covertly managed the prison. It served as the location where Sith Lords Darth Sidious and Darth Tyranus detained the rogue Sith Lord Maul before he escaped with assistance from Death Watch.
Years afterward, the Galactic Empire controlled the prison, defending it with ray shields, reinforced structures, anti-aircraft weaponry, TIE fighters, and stormtroopers. The defiant crew of the Ghost discovered that the Inquisitors were holding Jedi Master Luminara Unduli and attempted a rescue. In the process, former Padawan Kanan Jarrus encountered the Grand Inquisitor.
The Spire, situated on the planet Stygeon Prime, was a highly classified fortress embedded within the mountains of one of the planet's most desolate regions. Its name aptly described its architectural design. Although its origins and the identity of its builder are unknown, the Dark Lord of the Sith Darth Sidious made extensive use of the facility before the rise of the Galactic Empire, primarily as a containment facility.
Accessible only by air, entry was achieved through one of two docking bays. The Spire's robust walls featured a limited number of windows, constructed with equally thick transparisteel. The material's density distorted the view for anyone attempting to look out, and conversely, only allowed faint, weak rays of light to penetrate the interior. The Spire's gloomy, confined atmosphere enhanced its already dungeon-like construction.
Protected by both blast-proof construction and ray shields, the Spire rendered scanning impossible. Further defense was provided by surface-to-air weapon systems, each linked to a sophisticated sensor array, as well as ships that patrolled the surrounding airspace. During the Clone Wars, the Confederacy of Independent Systems managed the facility's daily operations, followed by the Galactic Empire, whose garrisons of battle droids and stormtroopers continuously patrolled the prison's intricate network of passageways, corridors, tunnels, and exterior balconies.
During the Clone Wars, the Spire was secretly operated by the Confederacy of Independent Systems. Following Darth Sidious' capture of Darth Maul on Mandalore, Sidious and his apprentice Count Dooku transported Maul to the Separatist's concealed prison on Stygeon Prime. There, Sidious and Dooku subjected Maul to brutal interrogation. After Sidious' departure, Dooku continued to interrogate Maul, seeking information about his Shadow Collective and his contacts within the underworld. However, Commander Saxon and [Rook Kast](/article/rook_kast], a pair of Mandalorian super commandos dispatched by Almec, Mandalore's Prime Minister, arrived to free Maul. They succeeded in liberateing Maul, escaping the prison, and evading the prison's battle droid garrison.
Following the conclusion of the Clone Wars, the Spire fell under the control of the newly established Galactic Empire. Luminara Unduli, a Jedi Master, was imprisoned there after her capture and subsequently executed. Her remains were kept within her former cell to lure out any survivors of Order 66. Five years prior to the Battle of Yavin, Gall Trayvis, an Imperial senator posing as a dissident, leaked information about the Spire, falsely claiming that Master Unduli was still alive. The Lothal rebel cell received this information and acted upon it, hoping to free her. Kanan Jarrus, the cell leader and Jedi, and his team infiltrated the Spire, but Jarrus and his apprentice, Ezra Bridger, discovered that Unduli was, in fact, deceased. The Grand Inquisitor revealed that Unduli had died with the Republic and that her bones were intended to lure the remaining Jedi out of hiding. Jarrus dueled the Inquisitor but was overpowered. He and the other rebels managed to escape past the Spire's stormtrooper garrison and flee.