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".

Episode 46
This episode in the 2003 anime series is named after the city, Robotonia, due to it being the topic of the episode.

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.