Star chamber

The star chamber was a room in the Doctor's TARDIS containing a small galaxy. The Seventh Doctor stored the Time Lord prison planet New Peerlessness in it after trapping the Struwwelpelters there. (AUDIO: Persuasion)

Vassarian's Battle TARDIS had a star chamber via which it drew power from the Eye of Harmony. The Dalek Time Strategist attempted to destroy the Eye through this room only for the War Doctor to sever the TARDIS' connection to the Eye. (AUDIO: Eye of Harmony)

The Mechonoid City had a star chamber. When the Emperor of the Restoration came to the city, the Mechanoid Queen took him to the chamber to analyse The Entity's rampage of the Restoration Empire. (WC: Planet of the Mechonoids)