Halo Array

"Whoever controls Halo controls the fate of the universe." - Captain Keyes.The Halos (as they are commonly referred to based on intercepted Covenant transmissions), alternatively known as the Sacred Rings by the Covenant, Fortress Worlds by their creators, and Installations by the AI Monitors that run them, are seven massive ring-shaped installations constructed by the Forerunner throughout the galaxy over one hundred thousand years ago as a last resort when combating the parasite known as the Flood. When nothing else could be done, they activated the rings which killed all sentient life within three radii of the galactic center. In addition to their role as weapons of last resort, the Halo installations are also research facilities. These facilities are chiefly used for studying the Flood.