They call it the Crimson Tower. It’s the MeteoTech's signal tower. Commands sent out here relay through facilities across the world to control the robots. In other words, you're looking at MeteoTech's brain! — Wave the Swallow, Sonic Riders: Zero Gravity
The Crimson Tower is a round, large, silver/grey mechanical structure several stories tall surrounded by a flat, mechanical complex. The base of the tower has a few vents and a MeteorTech banner. The top round segment of the tower has air vents and several yellow lights in two circular paths at the edge of the segment and at near the centre.
The Crimson Tower's purpose is to relay any transmitted signals from MeteorTech to facilities across the world in order to control the world's SCR-GP robots. As described by Wave, the Crimson Tower is essentially MeteorTech's "brain".
Later, Team Heroes followed Eggman to the Crimson Tower and crossed paths with the Babylon Rogues outside it where Jet challenges Sonic to a race inside the tower for obtaining all of the Arks of the Cosmos and the title of fastest in the universe. The teams raced each other in the tower and reached Eggman's main room there where they foiled the doctor from controlling the world's robots. Since all Arks of the Cosmos are brought together, Babylon Garden was brought below the surface. However, SCR-HD appeared at the Crimson Tower and stole the Arks, becoming Master Core: ABIS and a giant black hole that threatened to consume the world. The Crimson Tower was severely damaged by it while the heroes went to stop Master Core: ABIS.
After the events, it is not known whether the Crimson Tower was still intact or not from the incident.
Map including Crimson Tower (eastern point on peninsula)