The City of Excess

The Children of Joy live in an underground city beneath their featureless planet. It is an indeterminate distance from the L Gate, and close to the abandoned array first discovered by Cayne Neverwinter.
The lift descends from the barren surface of the world to a small hilltop raised area built within a massive underground cavern. The Children's motor pool is nearby where you can see at least fifty of the hover tanks parked in a neat formation. The lift is large enough to deloy them to the surface five at a time if a military response is needed on the surface for whatever reason. 
The city itself is carved into the rock of the planet and most buildings are lit from within by soothing purple lights. The cave roof itself has lights of the same hue embedded in it, though they are more haphazardly placed and remind you of stars.
The main attraction within the city is the large Quantum Construct Cube where Children of Joy can shed their personalities from their biomechanical frames, interacting as one within a giant central processor. This building is heavily guarded both by physical security systems, arcane wards, and a battalion's worth of heavily augmented guard robots. 
There are few Children of Joy inhabiting their physical bodies at a time, generally only doing so when interacting with the physical world is mandatory to achieve a specific outcome. The city is large and feels maintained but largely empty.