Iceworld (later the Nosferatu II) was a trading colony for space travellers that was located on the dark side of the planet Svartos in circa 2,000,000. It was, in truth, a vast spacecraft. Honeycombed with warrens and high chambers of ice, some with walkways, the spires of Iceworld reached far above the surface of the planet. It had a control room. Iceworld was a tourist attraction mecca and home of the Dragon, a biomechanoid who guarded the dragonfire. In reality, Iceworld was a vast spacecraft which had taken Kane, a criminal, from his homeworld of Proamon to Svartos.
Iceworld was also the home of Ace, once a time storm had transported her from Perivale on Earth in 1987 to the planet. She worked there as a waitress at a Iceworld's ice cream parlour. Iceworld was the stopping-point of the small-time criminal, Sabalom Glitz. At that time, Kane controlled, and had built, a small private army in Iceworld.
With the dragonfire acquired and Iceworld revealed as a ship, Iceworld lifted off to Savartos. Kane was confronted by the Seventh Doctor about the futility of his plans of vengeance against his (now-extinct) people. After Kane committed suicide and his original ship, the Nosferatu, already destroyed by Kane, Glitz took possession of it and renamed it the Nosferatu II, along with Melanie Bush, who decided to stay with Glitz to help manage his affairs and (hopefully) to keep him honest. (TV: Dragonfire)
One of the many versions of Clara Oswald created after she entered the Doctor's time stream appeared on Iceworld. She saw the Seventh Doctor as he was clinging onto the edge of a cliff. (TV: The Name of the Doctor)