UNSC Training Facility Bravo
From Halopedia, the Halo wiki
It is a large indoor environment with different close-quarters environments, including small buildings and tight corridors, that is used by veteran drill instructors who favor hands-on combat training, as opposed to more advanced methods such as a War Games simulator. Regardless, the training facility was later replicated into a War Games simulation by the UNSC. There is a mock-up of a Kig-Yar Sniper on a three-story building, and also devices built into a wall that when triggered by nearby movement, will display silhouettes of armed Jiralhanae, supposedly to simulate a combat environment.
It had several labeled training sections, including M1, K1, and K2. The primary gates on the facility were to remain closed during training hours of 6:00, 10:00-13:00 and 14:00-17:00.
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