The Sith Citadel is one of the many locations in Lego Dimensions 2: The Rise of Enoch, from the Star Wars franchise.
The Sith Citadel, also called the Citadel, was an ancient Sith temple located on the hidden Sith world of Exegol. It was the headquarters of the Sith Eternal cult following the demise of the last two Sith Lords at the Battle of Endor and contained the Throne of the Sith, which the resurrected Dark Lord of the Sith, Darth Sidious, intended to to serve as the seat of his new Empire.
The Sith Citadel on Exegol was one of the earliest bastions of the Sith.
At some point during the reign of the Galactic Empire, Darth Sidious had two Sith wayfinders created to guide the way to the Citadel on Exegol. One was made for himself and stored within his throne room upon the second Death Star, while the other was given to his apprentice, Darth Vader, who kept it in his castle on Mustafar.
Sometime following the Battle of Endor, Sith loyalists chose the Citadel to be their new fortress, as they believed Moraband—while once the greatest fortress of the Sith—was too likely to be discovered. At some point, Sidious was resurrected and came to reside at the Citadel, where he guided the actions of Snoke, whom Sidious himself had created sometime before, both to test Kylo Ren's worthiness to take up the Sith mantle and to rule over the First Order while Sidious moved in the shadows.
Meanwhile, Jedi Master Luke Skywalker believed the conflict with the Sith was not over despite Vader's conversion to Anakin Skywalker and the death of Sidious above Endor. He and Lando Calrissian set out to locate the Emperor's wayfinders in the hopes of locating the Citadel on Exegol, where Luke believed he could end the conflict with the Sith once and for all. Luke's hunt went cold on Pasaana and he ultimately went into exile on Ahch-To following the fall of his nephew, Ben Solo.
In 35 ABY, Supreme Leader Kylo Ren arrived at the Citadel with the intent of killing the resurgent Emperor, whom he believed was a threat to his power. However, Sidious convinced Ren to instead take up the hunt for the Jedi apprentice Rey, who was in reality his granddaughter, in exchange for the Sith Eternal fleet and the might of the Final Order. However, Ren was turned from the dark side through the combined efforts of Rey and his mother, Leia Organa, and became Ben Solo once again.
After using Ren's wayfinder, Rey arrived at the Citadel and confronted Sidious. She refused Sidious's offer to become a Sith and, joined by Ben, attempted to kill the Dark Lord once and for all. Instead, Sidious used their dyad in the Force to restore his mortal body. From the Throne of the Sith, Sidious unleashed a storm of power that nearly destroyed the Resistance forces. However, empowered by the voices of all the Jedi who came before her, Rey stood and defeated Sidious by reflecting his lightning back at him. The resulting shockwave destroyed the Citadel, and left Rey alone, where she effectively died. Rey was revived by Ben Solo, who used Force healing in conjunction with his dyad with Rey to trade his life for her's. Ben died in the ruined Citadel, and became one with the Force. Rey flew away from the ruins in Luke Skywalker's X-Wing.