Gamma City is one of the three cities created by the Vestals (the other two being Alpha and Beta), and it's connected to the Vestal Palace. It was the first city to invade New Vestroia. Like the other two it has a Dimension Controller as well. The Dimension Controller was destroyed after the battle of Mira Clay and Gus Grav against Ace Grit and Dan Kuso. Once this battle ended, the city started to fall apart while the Resistance rode out on their Bakugan, but no lives were taken. The Gamma City Dimension Controller was destroyed in Wall to Wall Brawl. Spectra Phantom and Gus Grav were in charge of this city, while the Vestal Palace was under change of Prince Hydron.
Gamma City is located deep underground and the only way to get there is by a special elevator. Right below the city is an underground pool of lava. It is not inhabited by anyone instead, it is a research facility for Mechanical Bakugan. This was the place where Cyborg Helios and Hades were made. Once Dan Kuso and Ace Grit destroyed their Dimension Controller, however, the building started to come down and the place was evacuated with the debris being burned by the lava.