The Imperial Hall was a fortress on the planet Ilari, where the First Autarch ruled with his family and advisors. It was built over a waterfall. During the reign of Tieran, it did not contain displays of wealth, only a paintinf of Tieran. After his overthrow, the painting was removed and wealth added. In 2373 the building was equipped with a detection grid.
Tieran, controlling Kes' body, stormed the Imperial Hall in 2373 with his followers and seized power. Tieran was subsequently removed when Demmas, the rightful Autarch, defeated his forces and assaulted the Imperial Hall with assistance from USS Voyager personnel. (VOY: "Warlord")