Sanctum of the Hierarchs

The Sanctum of the Hierarchs is the private quarters of the High Prophets on High Charity. They are restricted to virtually all other creatures, except the Honor Guard, Prophet and Elite Councilors, and high ranking Covenant officers, such as Rtas' Vadum and The Arbiter.

The Inner Sanctum features unique architecture, highly ornamented doors, and various other luxuries. The Sanctum has several entrances; One is via a lift in the Council Chamber, another is a large hallway where dozens of Honor Guards stand watch. The higher levels of the sanctum or the Far Tower also include three tenders for Phantom dropships.

Many events took place here, including the "exchange of hats" when the Brutes replaced the Elites as the Honor Guards, after the assassination of the Prophet of Regret. It was here that the Prophet of Truth and the Prophet of Mercy explained to the Arbiter his task of landing on the surface of Installation 05 and retrieving the Index from the Flood infested Library, which took place in two levels through the Sentinel Wall and the Quarantine Zone.

In the end, the Flood used Pelican dropships to land in the sanctum. It was one of the first areas to be infested; it was filled with spores and Flood "structures" when the Master Chief traversed the area in search of the High Prophet of Truth.

The room that Cortana is located in Halo 3 is the Sanctum. The Sanctum is connected to the reactor room that's not accessible in Halo 2 due to a series of locked doors. The room has been dramatically altered by the flood infestation and the widespread structural failures that occured as a result of high Charity colliding with the surface of Installation 00.