Emerald City, often shorted to Em City is the fifth cell block in Oswald State Correctional Facility.
Emerald City is an experimental unit in Oz. Founded by Tim McManus, Emerald City is an extremely controlled environment, with a carefully managed number of members of each racial and social group, with the hope of easing tensions among these various groups. The unit, unlike other units, offers rehabilitation programs to the prisoners. The prisoners are allowed to walk around and talk to the prisoners in the unit and they are allowed to play card games and board games, all in their own clothes (not like other units that demand prison uniforms).
Notable features that have appeared only in Emerald City:
- Cells made out of glass
- Open televisions at the cellblock center
- Built Classroom
- Prison uniforms aren't mandatory
- Laundry room
- Computer room
- Punishment cage
Em City is the main unit during the show, and most of the plot arcs happen in that unit.
Since the inmates in Em City have more freedom than prisoners in other units, the unit is preferred by the inmates, and to transfer out of Em City is considered a punishment.
The unit manager through most of the show is Tim McManus, although Martin Querns was also the unit manager for a brief time. The unit's Head CO at first is Diane Wittlesey, then Karl Metzger until his death, then Sean Murphy, then Travis Smith for a brief time, and then Sean Murphy again for the remainder of the series.