Citadel Inquisitorius was the headquarters for most of the Inquisitorius, located on the mountainous planet Prakith in the Deep Core. Here, the High Inquisitors received assignments and conferred with other Inquisitors. The citadel was a dark, fear-inspiring tower jutting forebodingly from the mountains. Inside, it had features similar to those of religious structures found galaxywide, with vaulted ceilings and massive obsidian columns; it also contained a number of detention cells and torture chambers used to interrogate the most resilient and dangerous prisoners.
Circa 17 BBY, Jedi Master Denia was captured by her former Padawan, Imperial Inquisitor Valin Draco. She was held deep within the Citadel Inquisitorius on Pakith and tortured. Her allies in the Alderaanian Resistance later tried to rescue her by attacking the Citadel, but she sacrificed herself during the battle to allow the Rebels to escape.