Lore:Castles and Coffers Volume III: Hel Ra Citadel
Imperial historians, most notably Dubicius of the Colovian Highlands, speculate that Hel Ra Citadel was constructed sometime during the second Yokudan "Warrior Wave" as it swept into the Alik'r desert of western Tamriel. Most believe, as is obvious from its title, that it was built to protect the nearby Yokudan city, the name of which has been lost to sand and time. But the Yokudans did not name the Citadel; modern Tamriel did. The structure could have long predated the city it protects. It could have been a foothold for one or both invasions, it could have been one of many forts now lost, or even a fortressed training ground. In myth, sword saint training for maintaining "sword magic" was notoriously rigorous, and even an invasion force would require a space for that. Some say that where the Citadel now stands was first a Nedic fort, that the Yokudans conquered it, built on top of it.
According to the Imperials, all anybody knows for certain is that the Citadel has been sealed since the Yokudan retreat. No one has ever been inside. There are claims and stories, of course, all false. Imperial records state the Empire has failed to enter, and expeditions by the Redguard themselves have failed to bypass the Citadel's front door. Be it through spellcraft, or a trick of its construction, no army or siege engine has ever been able to defeat those walls. What treasures, what ancient secrets could await inside? Will the Citadel's gates ever open?
Said Imperial Magistrate Albus: