The Damascus Materials Testing Facility was a UNSC base located in the Chi Ceti system on planet Chi Ceti IV, in the UNSC-controlled, Outer colonies. This top-secret base is where the Spartan-II supersoldiers were relocated for their final stage of training and the inclusion of their MJOLNIR Mark IV Battle armor in 2525. Though it was only manned by three technicians, it had a curious feature, which was that a dozen AIs could operate and utilize the facility in close proximity to one another, which is typically impossible under normal circumstances for technical reasons. It is implied that Dr. Catherine Halsey worked here for a while to refine the MJOLNIR armor series. The Mark VI MJOLNIR Powered Assault Armor/EOD variant was also created and constructed here. There were also obstacle courses for the SPARTAN-IIs to become accustomed with their new armor.
Right after the Spartans received their armor, the facility was attacked by nearby Covenant activity, the Unrelenting. All personnel were evacuated and the AIs were deactivated by Halsey when she removed them in the form of cubes of data. Spartans John-117, Kelly-087, and Sam-034 boarded the Unrelenting and destroyed the Unrelenting by detonating Nuclear missiles requisitioned from their Pelican drop ship on one of the plasma cannons.
The facility may have been recaptured as a commission was held to figure out whether to approve of a variant of MJOLNIR or not.