The Watcher Prison Facility was a prison for Survivors that Will Grey and his allies attacked at the beginning of the second Episode of the game.

Will is forced to fight through several different areas of this facility, shutting down power cores along the way in order to turn off the power to security and allow the Survivors to rescue the prisoners.

This facility was apparently used for experimentation on humans, according to what Tavi says once you rescue him near the end of the level. He also says that the prisoners' cells were extremely tight and cramped (something Will gets to experience first-person at the beginning of the third Episode of the game).

The operation to rescue the prisoners was a success, allowing Will and these newfound allies to return to The Ark.