- “Here rests the vanguard of the Great Journey. Every Arbiter, from first to last. Each one created and consumed in times of extraordinary crisis.”
A large suspended sarcophagus held the special Arbiter armor until it was needed again. It is thought that this is not the same armor each time, as all Sangheili would (in reality) be different sizes. This is very noticeable between past Arbiter Ripa 'Moramee and current Arbiter, Thel 'Vadam, making it likely a sham by the Prophets, who keep the armor less advanced for religious reasons. This theory is confirmed by the destruction of Ripa 'Moramee's corpse at the Apex, meaning that the original armor of the Arbiter was not shared by all Arbiters. Additionally, should the Prophets' order to kill Thel 'Vadam have succeeded, his armor would not have been salvaged either.
The Mausoleum of the Arbiter also contained the (recoverable) remains of every Sangheili that has ever been designated as the Arbiter. A total of one hundred eighty-two caskets are present, spreading far up into the ceiling. Arbiters are only appointed in times of dire need, such as the Taming of the Lekgolo, the Unggoy Rebellion, and the Human-Covenant war, making this number of Arbiters unlikely.
The Mausoleum of the Arbiter initially appeared in the cutscene before the Halo 2 level, The Arbiter, where Thel 'Vadamee was taken there by Tartarus and his two Jiralhanae ushers. The Prophet of Truth and the Prophet of Mercy ordered Tartarus to release 'Vadamee and leave. After this, they started to converse with him about Sesa 'Refumee and the past Arbiters, ultimately appointing him the new Arbiter and giving him the ornate armor of the Arbiter there.
The Mausoleum was next seen some time later, near the end of the level Gravemind. Here, John-117 had to engage in a large-scale battle in order to go further into High Charity and find the platform with the Phantoms that were used to transport Truth, Mercy, Tartarus, Miranda Keyes and Sergeant Johnson to their respective locations.
After that, it was seen for the last time in Halo 2 on the level High Charity. Upon reaching the huge tower and looking down, the player could see it surrounded by a layer of clouds and a storm. Above it lies the Sanctum of the Hierarchs.
The Mausoleum was last seen visible in Halo 3 during the level Cortana. It is seen at different points through the "windows" formed by the Flood's consumption of the city. Energy cascades across the surface leaned dangerously over to the side and cables hung from the shattered bridges around the tower. The Mausoleum and the Vanguards of the Great Journey entombed within were destroyed when High Charity's reactor went critical, as spurred by SPARTAN-117 in the previous raid, and destroyed the Flood Infected city.
- In the early version of the level Cortana, Master Chief would have passed through the Mausoleum, encountering an army of Flood-infected Arbiters. This idea was scrapped however, when both Flood levels were redesigned, possibly because the Arbiters would have been armorless. Another reason could be that over time, the Arbiter bodies could have decomposed like normal bodies after being in the caskets for so long. It is possible that some method of preservation is used in the caskets, but due to the fact that most Arbiters are only respected because of their title (if that much, being that the rank of Arbiter implies a great amount of lost honor, as Arbiters undergo their suicidal mission as a means to regain that honor), it is unlikely. Also, it is probable that most of the caskets were empty, as suicidal missions taken by Arbiters could make their bodies irrecoverable.
- It would seem that the Mausoleum was located close to the Detention Center, as seen in the cutscene level The Heretic. However, the path taken in Gravemind reveals the two to be much farther away from each other.