The Dark Vault is the home of the Dark Brotherhood's most powerful treasures and trophies as well as the main library of the Shadow Academy, housing thousands of years of history, philosophy, lore, and tactical manuals. Nearly all of the Shadow Academy courses are derived from information found in the library, and often students will come here to further their studies. Originally built on Lyspair, the Dark Vault was made of five levels, each with a different security access requirement. Students could only access the first level, while the Headmaster could go as far as level four. After the Evacuation of Lyspair, most of the Dark Vault's information was made digital and moved on board the Arcanum, though the same security exists as it did on Lyspair. When the Dark Brotherhood returned to the Antei System, information was restored to the original library, as well as increased security measures in the case of future attack. To a certain extent, in the case of attack, the Dark Vault is one of the safest places in the Shadow Academy.
The Dark Vault also maintains an auxiliary capacity with the Holocron Center of the Brotherhood, which only the Headmaster can access. Level Five of the Vault contains the ancient artifacts and treasures of the dark side, also only accessible by the Academy's steward, the Grand Master, the Deputy Grand Master, and other select members of the Dark Council. While Holocron Center information may only be accessed remotely, many holocrons that have not been thoroughly studied are left in the Dark Vault to be further explored by the Headmaster before being transferred to the Holocron Center.