"The world exists entirely within this dome. Outside the dome, there is nothing."
-Sergei explaining falsehood the Government wished to impose.
The Dome City is the host of many locations in Custom Robo Battle Revolution. A large majority of the game takes place within this structure. It is also houses a majority of the population and built as a safe point away from Rahu.
Following the rampage of Rahu throughout the world humanity was left in shambles. With most of the world destroyed and lifeless, the survivors sought out a new home. As time passed they eventually arrived at an area with the most minimal damage to it and developed a construct large enough for all of the worlds population. This was known as the Dome and society once again developed and advanced past it's previous condition. Soon after the success of building a new home, the Government developed a way to ensure that citizens would never have to deal with the traumatic stress of Rahu ever again, coming to the decision to create the Memory Erasure Device. With this in effect the government decided that the best way to ensure the world remains stable was to deceive the memory of the citizens. From with the MED in effect they developed a falsehood and implanted it into everyone's memories :the world exists entirely within the dome, beyond that nothing else existed.
The Dome also served a secondary purpose, defense against Rahu's possible return. For this the Police Squad developed a license grade consisting of highly skilled commanders, the S Class. The purpose of this group was to ensure that should the Autonomous Robo ever return, they were prepared to fight agaisnt it just as humanity had ages before.