Kingdom is an underground research and detention facility in the City of Glass. It mainly focuses on developing the Reflection project which can be used for controlling people's emotions and behaviour. It also detains prisoners such as Aline Maera, who was later rescued by Faith Connors. The facility is one of the Conglomerate's biggest secrets, and its location is only known by the Corporate Houses' members and their close associates. Dogen instructed Faith how to access the facility when she attempted to rescue her mentor and a man who adopted her, Noah.
Kingdom is located in Development Zone G, below the Omnistat Tunnels. The main entrance to the facility is unknown, so Plastic hacked an orange blast door for Faith. She then used the sewers to enter it. The location is only known to the Conglomerate and their associates, so its existence is unknown to even the most affluent hiCaste members.