The UNSC Maximum Security Detention Facility is a prison run by the United Nations Space Command. It made it's first appearance in Recreation Chapter 4. The facility was where Agent Washington was being held for breaking into Command.
The facility is represented on the Halo 3 map, Orbital. At the bottom of the escalator are stations which are used for prisoners to answer calls, as seen in Recreation Chapter 4 when Caboose calls Washington.