Argus Panoptes had 100 eyes.
The mythical Greek monster made for a formidable watchman, as while some eyes slept, there were always eyes awake.
Named after said giant, an all-seeing "panopticon" prison system was mooted by English philosopher and social theorist Jeremy Bentham in the late 18th century. The design involved a circular structure with a tower at its centre, where guards are able to view every cell around the perimeter.
Consequently inmates are unable to tell when, or whether, they are being observed. Architecture alone could control their behaviour. As Bentham stated, his prison system would create "a consciousness of permanent visibility as a form of power, where no bars, chains or heavy locks are necessary for domination". Or, more boastfully, "a mill for grinding rogues honest".
Hence, the ideal outcome for Bentham, and his prospective clients wanting to save money, was that the subsequent modified behaviour would ultimately end the need for the tower to be manned.