Terra-Sphere Control tower

The  was one of the towers built by Dollar Intergalactic for terraforming Isen VI in the 25th century. This tower was the headquarters of the Terra-Sphere Control.

The foundation for the tower was a terraformer missile that hit the ship of Rann-Korr. This gave the Hyperion access to and control over the whole terraforming process. Coolant gases were used to protect the lowest levels of the tower from the heat of Isen VI's core.

When the Terra-Sphere Control detected the Twelfth Doctor and Clara Oswald's arrival, the intruders were brought to the tower. (COMIC: Terrorformer)