The information he uncovered revealed the location of Installation 07. In 2555, while exploring the Shield world Trevelyan, archaeologist and Forerunner cultural expert Luther Mann discovered records buried deep within its vast information pathways and proceeded to translate them. However, John-117 deactivated the installation before it was able to finish its activation sequence.
Ī more comprehensive readout was later observed on the Ark during the Battle of Installation 00 by Thel 'Vadam, John-117 and the Prophet of Truth, once again displaying that Installation 07 was on standby mode, waiting to receive the signal to fire. A readout from Installation 05's Control Room showed that Installation 07 was fully prepared to fire on demand. In 2552, during the Battle of Installation 05, a signal was sent to this Halo from Installation 05, putting it on standby mode. After arriving at their final designated coordinates in the galaxy, under the command of the IsoDidact, the seven installations fired in unison to eradicate all sentient life in the galaxy, successfully containing the Flood parasitic lifeform.
At the command of the IsoDidact, this Halo was sent through the portal containing the (presumably) Flood-infected Forerunners processed by the Composer, the timelocked Graveminds (of which approximately ten had already developed), as well as any remaining species infected or otherwise to remain untouched as a sacred tomb "to millions" for approximately the next one hundred and one thousand years. The installation survived the Forerunner-Flood War and was present at the Lesser Ark as one of the final seven when they were deployed for the final time. This reduced Installation 07's diameter to 10,000. After 032 Mendicant Bias was defeated in his plan, the IsoDidact, out to save the life stored on the ring's interior, arrived and ejected the damaged sections of the Halo in order to reduce its mass allowing it to transition through a small slipspace portal, necessary due to Installation 07's severely drained power supply. Thus, 032 Mendicant Bias enacted a plan to save the installation for the eventual use of eradicating the Forerunners. The cure was thought to be hidden in the genetic memories of humans, and they were also observed showing immunity to the parasite as well. Its diameter was originally 30,000 kilometers, until it was nearly destroyed after a failsafe collision course orbit with a Failsafe Planet. Its collision course with the Failsafe Planet was enacted by rogue Lifeworkers and presumably the Master Builder in order to stop 032 Mendicant Bias, in the event they failed or finished finding a cure for the Flood on the Installation. Two humans, Chakas and Riser, were deposited on the surface of the ring world after being torn from the ship of their Forerunner companions, Bornstellar and the Ur-Didact, who were dropped to the besieged world below. This rampancy was onset through conversation with a being known as the Primordial, that was detained on the installation for interrogation. The Installation received its first activation above the San'Shyuum Quarantine worlds to eradicate their rebelling populaces.
Some time after its construction, Installation 07 was stolen by 032 Mendicant Bias as a result of induced rampancy.
Installation 07 was the main setting of the events in Halo: Primordium, prior to the firing of the seven rings.