The Beacon Vault was a large underground chamber hidden beneath Beacon Academy. It could be reached via an elevator, which was also connected to Professor Ozpin's office. It is presumably the location of the Relic of Choice.
In the "Volume 9 Bonus Ending Animatic", it is revealed that Vale was destroyed by Salem during her search for the Relic, which included the school as well. However, it is unknown if she acquired it yet.
The Vault is vast and dimly lit by wall-mounted torches that cast a pale green light. The elevator leading down to the Vault is located at one end of the corridor and Amber and her life support machines are at the other end. The corridor appears to intersect perpendicularly with another, but the other branches have not been shown.
Pyrrha, Ozpin and Jaune Arc return to the Vault in "Heroes and Monsters" in order to complete the transfer. However, Cinder Fall arrives and kills Amber before the transfer can be completed. The powers of the Fall Maiden thus pass to Cinder. Jaune and Pyrrha escape to find Qrow, Glynda and Ironwood as Ozpin prepares to fight Cinder.
After Ozpin's battle against Cinder, the Vault is rendered inaccessible due to the Grimm occupying Beacon Academy.
Following this, Salem instructed her Grimm to search for the Relic at Beacon. However, as it was made more difficult to find than at the other Vaults, she has yet to acquire it.
The scene with Pyrrha Nikos and Ozpin's Group walking through the Vault in "Fall" was, according to everyone, one of the most technically difficult and time consuming scenes in the entire Volume.[1]
The Vault appears in "Magnetic Personality", the 8th episode of RWBY Chibi, where it is clearly marked on the Beacon Tower elevator as "Super Secret Vault (Do Not Enter)". Team RWBY decide to visit the Vault, where they encounter the janitor, who turns out to be Shopkeep.
It is unknown if the Relic of Choice is located here, as Salem has yet to find it.
