The Imperial Sanctum, the private residence and working offices of the Galactic Emperor Palpatine, was constructed in the Imperial Palace during the refurbishment of 18 BBY. Consisting of several chambers including the Emperor's private office and bed chamber, a throne room, and the chambers of Darth Vader, the suite of chambers were used primarily by Palpatine, Vader, and their functionaries and aide-de-camps. The Emperor and Vader would often invite guests, such as Prince Xizor of Black Sun, to discuss things of import within these rooms.
Following the Emperor and Vader's deaths at the battle over Endor in 4 ABY the throne room in the Sanctum was placed in a state of formal mourning; a black shroud was draped over the throne during this turbulent time. When Sate Pestage declared himself Emperor, he took up residence in the Sanctum and sat on the lower throne, not daring to ascend to the higher throne room in fear of outright dissension by other Imperials. During this time Emperor's Hand Mara Jade escaped her prison in the Palace and entered the Sanctum where she stole the black shroud from the throne room and used it to cloak herself as she escaped the Palace.
After Pestage's overthrow, the Tribunal governed from the chamber where the Imperial Ruling Council had once sat. Subsequently, Director of Intelligence Ysanne Isard used her powers as head of the security apparatus to remove all rivals and seize control of the entire administration, making herself de facto Empress, but she eschewed the formal trappings of power, and her existing office took over the functions of the throne room as a control center and high-level audience chamber.
A a far more sparse environment than the summit throne room, the command chamber was vast and cavernous. The throne itself jettied out on a long, blade-like balcony in a vast empty space; the only entrance lay at the far end of the balcony guarded by a pair of the Emperor's Royal Guards.
Other chambers in the Sanctum included the Emperor's working office which was unadorned save for a desk and a holoprojector and several pieces of prized artwork. Similarly, Darth Vader's office was kept bare but for a series of datascreens that kept him up to date on galactic happenings from across the Empire.
- The New Essential Chronology