It is a large indoor environment with different close-quarters environments, including small buildings and tight corridors, that is used by "veteran instructors" to train UNSC Marines. There is a mock-up of a Jackal Sniper on a three-story building, and also devices built into a wall that when triggered by nearby movement, display silhouettes of armed Brutes, supposedly to simulate a combat environment. It is used by instructors who favored hands on combat training, as opposed to a simple rifle/firing range, or a neural simulator.