Panopticon

The Panopticon was the main room of the Capitol on Gallifrey. The Eye of Harmony was secretly kept under the Panopticon. (DW: The Deadly Assassin) The Panopticon had six sides, as that number was revered on Gallifrey. (EDA: The Ancestor Cell) When Gallifrey's suns shined on the Panopticon, the interior would shine turqouise. (EDA: The Tomorrow Windows)

The name panopticon was likely derived from opticon, the Gallifreyan word for the ancient village meeting place. (DWA: Blind Fury)

Out-of-universe, the name derives from Greek, meaning "all seeing".

The Panopticon also refers to the tower in the center of a prison from which the guards can see into all the cells freely at any time. Thus, the prisoners never know when the guards might be looking and must always be on good behavior. In this way the Panopticon represents form of social control.