Installation 05 (Earth-2946)

"Whoever controls Halo controls the fate of the universe."

- Captain Jacob Keyes

Installation 04, also known as Alpha Halo, or simply Halo, was one of seven ring-shaped superweapons that were part of the forerunners' Halo Array. Located in the Soell system, in the Orion Arm, it was the closest Halo to the human sphere.

The Covenant revered Installation 04 as the First Sacred Ring. After its destruction at the end of the Battle of Installation 04, the Ark started constructing a replacement ring for Installation 04. After the replacement was destroyed during the Battle of Installation 00, the Ark built yet another replacement.