Throne Room

Throne Room is a chamber located on the 10th Floor of the Great Tomb of Nazarick.

Background
The Throne was an area designed by the guild, Ainz Ooal Gown to welcome invaders who managed to penetrate the defense of the dungeon. There the guild members would assemble here for a final showdown. The Overseer Guardian Albedo was the only NPC allowed to be stationed here, acting as the overall commander to the Floor Guardians.

Sadly no players had ever reached the Throne Room, not even the Union of Eight Guilds when they launched their invasion of Nazarick, making the chamber little more than a decoration.

The Undead King Arc
Momonga wishing to spend the last hours in Nazarick decides to head to the Throne Room as a final act as Guildmaster. He has the Pleiades accompany him to the chamber where he sits upon the Throne of Kings waiting for the YGGDRASIL server to shut down. Momonga finds that he had dozed off and found that he was still in the game. Not only that NPCs had gained sentience and the tomb had somehow been transported to another world.

After scouting the outside of Nazarick, Momonga assembled all the NPCs in Nazarick to declare that his name will be 'Ainz Ooal Gown'.

The Emissary of the King Arc
Ainz later visits the Throne Room, finishing up a personal survey of the Floor Guardians. Albedo being the last person on his list, he tries to find her quarters only to have her tell him on a [Message] that she has been living in the Throne Room since her creation. Ainz finding this to be unacceptable decides to assign her permanent quarters on the 9th Floor.

The Bloody Valkyrie Arc
Ainz Ooal Gown upon hearing that Shalltear Bloodfallen rebelled against him, rushes from E-Rantel to discern the situation himself. He and Albedo access the dungeon Administration System to determine her allegiance and confirmed that she was brainwashed by an outside influence.

Later after Ainz successful defeated and slain Shalltear, Pandora's Actor had brought several piles of gold coins to prepare for her resurrection. The Floor Guardians assembled to prepare for an event when the resurrection failed to free her from her comprised mind.

The Lizard Man Heroes Arc
The Floor Guardians assembled here once again to update Ainz Ooal Gown on the progress of their individual tasks. Though the main topic was to hold Cocytus accountable for the failure of the Army of Death against the Lizardmen Alliance. He was spared from serious reprisal for his failure and his request to spare the lizardmen thanks to Demiurge's argument in conquering them as an experiment.

Layout
The Throne Room lies in the deepest reaches of the infamous dungeon. The Lemegeton stands between it and the rest of Nazarick, acting as a final defense for the heart of Nazarick.

The room itself is an exquisite piece of work. A wide, high room, enough for several hundred people, with a high ceiling and surrounding walls that were predominantly white, with golden decorations as highlights.

Hanging from the ceiling were numerous chandeliers made of precious stones of all colors of the rainbow, and emitted a fantastic, dreamlike radiance. Numerous flags emblazoned with different symbols, each for one of the Supreme Beings, hung from flagpoles embedded into the walls.

Throne of Kings
In the center of this room that was tinted gold and silver, was a flight of stairs about 10 steps high. Atop these stairs was a gigantic throne, carved out of a single piece of crystal, whose back was high enough to touch the ceiling above it. A huge red banner hung down behind it, proudly displaying the symbol of the guild.

Trivia

 * From here various dungeon systems can be accessed by the Guildmaster.