Robotonia

Robotonia is a robot city, populated entirely by robots, that was founded by the Blue Knight. It strives to be a safe haven for robots everywhere and where they are allowed to "be free". It is showed to be planned properly, and its leader is actually not the Blue Knight but Shadow

Location
It is located in the South Pole. The castle was then shown to be actually a spaceship, which went to space after the battle.

Origin
It was built after the humans declared war on robots and tried to wipe all robots out of Metro City, following an incident.

Army
Robotonia's army is composed entirely of robots that overthrew the humans, lead by Duke Red.