Monopole (モノポール,Monopōru?) is the primary setting in Sonic Riders: Zero Gravity. It is a large and highly advanced metropolis referred to as "the famous city of the future".
Monopole is an advanced and high-tech streamlined city area. It has tube-like roads with hover-cars, colossal building structures and robot-workers walking on the streets, making it resemble something futuristic.
It has a large variety of different capital-city elements, such as mass transport by train, parking lots, a museum, gardens, and freeways. Besides including the metropolis of Megalo Station, it potentially also includes other areas, such as the chrome canals of Aquatic Capital, and exospheres containing an abundance of flora like Botanical Kingdom (depending on translation).
Monopole and its regions' reliance on robotic technology is exploited by Dr. Eggman during Sonic Riders: Zero Gravity. Operating behind the scenes of his shell company MeteorTech, a leading security manufacturing company, Eggman worked towards completing his Eggmanland project; by using Monopole's dependency on technology, Eggman saturated Monopole's industrial economy with his own SCR-GP model robots, planning to later seize control from Crimson Tower with his robots once his machines had thoroughly infiltrated society.
During the events of Sonic Riders: Zero Gravity, Eggman plans for Monopole were compromised when additional Arks of the Cosmos showed up and took control of his Mother computer, causing the robots to run amok on their own for the purpose of returning the Arks of the Cosmos to Babylon Garden. As a result, Monopole was overrun by robots fanatically searching for the Arks of the Cosmos. While Team Sonic was in Monopole, the group was attack by the robots, invoking Team Sonic to search Monopole for a way to stop them. Meanwhile, the Babylon Rogues came to Monopole to find the Arks of the Cosmos. Eventually though, Monopole was freed from the rampaging robots after Team Sonic, Amy Rose and the Babylon Rogues disabled Eggman's mother computer.
Monopole is given a name in the Japanese release of Sonic Riders: Zero Gravity, but it is not given a name in English-language regions.
Monopole may or may not be a part of the United Federation; In the opening sequence, G.U.N. (referred to as "the international security organization") is said to be investigating the robot disturbances, but its presence is never seen in Monopole.