The Citadel Var'Theldun was a structure located on the planet Romulus.
It was the third most important building in the capital of Val'danadex Trel; behind both the Imperial Romulan Senate and the Praetor's Palace. The Citadel was the home and headquarters of the feared Romulan intelligence service; the Tal Shiar. Many tended to avoid this structure with some even going as far as trying to prevent the shadow of the building from touching them in the belief that it would mean imprisonment within its walls. Those that enter the Citadel were doomed to never appear in the streets of the capital again and instead suffer a life on a far off penal colony in the Romulan Star Empire. (Last Unicorn RPG module: The Way of D'era: The Romulan Star Empire)