Floor 1056

Floor 1056 was one of over a thousand decks on a Mondasian colony ship. Following the ship's arrival at a black hole, a team of engineers travelled to Floor 1056 to reverse the rear thrusters. Unable to return to Floor 0000 due to the black hole's time dilation, they spent the rest of their lives on Floor 1056.

A thousand years later, the descendants of the engineers inhabited the floor, which had transformed into a huge city. However, the city had significantly degraded due to its close proximity to the ship's rear thrusters. (TV: World Enough and Time) To survive, the inhabitants evolved into Mondasian Cybermen - whose existence had been at least partially influenced by - and used the city as their base of operations in preparation for their final assault on the ship. (TV: The Doctor Falls)

Colonisation
The colony ship was travelling from Mondas to pick up some colonists. On day 43, the ship almost traversed into a black hole. Twenty engineers, including chief engineer Franq, (PROSE: Jorj) were sent from Floor 0000 to Floor 1056 to reverse the rear thrusters. After completing their mission, the engineers found that they were unable to return to the flight deck, and so remained at the bottom.

Degradation
Due to their inability to return to Floor 0000, the engineers spent the rest of their lives on Floor 1056, eventually establishing an entire civilisation on the ship's bottom floor. Their descendants lived in a huge city, but as the centuries passed, the city degraded due to its close proximity to the ship's rear thrusters. A thousand years later, Floor 1056 had become unsustainable for human life, with most of its population living lives of poverty in ruined apartment blocks. (TV: World Enough and Time)

During the city's degradation, arrived on Floor 1056 (TV: The Doctor Falls) sometime after escaping Gallifrey. (TV: The End of Time) He attempted to escape the colony ship but flew his TARDIS too quickly in close proximity to the black hole, burning out his dematerialisation circuit in the process. The Master then "killed a lot of people, took over the city [and] lived like a king" until the people rebelled against him. Unable to escape, he adopted the disguise of "Razor" (TV: The Doctor Falls) and began working in the city's hospital.

Rise of the Mondasian Cybermen
Eventually, the hospital began Operation Exodus, a scheme with the intent of transforming the inhabitants of Floor 1056 into cyborgs that could survive not just in the city, but on the journey to Floor 0000, where the humans would take command of the ship. (TV: World Enough and Time) However, the Master manipulated the development of the operation to ensure that the cyborgs produced by Operation Exodus were a race of Cybermen, (TV: The Doctor Falls) with which the Master could conquer the galaxy. (PROSE: Alit in Underland) The "patients", an early evolution of Mondasian Cybermen, would not only escort people from the city to the hospital for Cyber-conversion, but would also travel to the higher floors to capture any remaining humans for conversion, as they did to the human crew members on Floor 0000. (TV: World Enough and Time, PROSE: Jorj) One patrol of patients travelled to Floor 0507, but never returned. (TV: World Enough and Time, The Doctor Falls)

Following the arrival of the Twelfth Doctor's TARDIS on Floor 0000, Bill Potts was shot through the heart by Jorj, the sole individual and non-human left from the original crew, and was taken to Floor 1056 by a team of patients. After months of recovery, Bill woke up in the city's hospital with a cybernetic heart. After meeting Razor, she spent ten years on Floor 1056, waiting for the Doctor while working in the hospital. As the technology for Operation Exodus continued to evolve, eventually, Razor explained the purpose of the operation, (TV: World Enough and Time) hiding his intentions to use the people of Floor 1056 as his personal Cyber-army. (TV: The Doctor Falls, PROSE: Alit in Underland) During these years, Bill and Razor watched security footage of Floor 0000 from the hospital, until eventually, the Doctor, Nardole and Missy began entering one of the lifts to Floor 1056. That night, she and Razor broke into the hospital's Conversion Theatre to get to the lifts, only for Bill to be captured by the surgeon and the nurse, the whole scenario having been a trap set up by the surgeon, nurse and Razor. Against her will, Bill was converted into the first full Mondasian Cyberman.

Two hours later, the Doctor, Nardole and Missy arrived in a lift behind the Conversion Theatre. The Doctor and Nardole snuck into the Conversion Theatre and found the converted Bill in a small storage room. Meanwhile, Missy investigated a computer terminal and found the ship's planet of origin, before Razor confronted her and revealed his true identity. The two Masters then went to the Conversion Theatre, (TV: World Enough and Time) knocking out the Doctor and taking him to the hospital roof, followed by Bill. On the roof, the Masters gloated over their victory until the Cybermen began attacking the hospital; the Doctor revealed that he had changed the Cybermen's definition of humanity shortly before being knocked out, so that the Cybermen registered lifeforms with two hearts as human. After a brief battle, the trio escaped with Bill in a shuttlecraft procured by Nardole from a loading bay, albeit after the Doctor was severely wounded by a Cyberman.

While the group escaped to Floor 0507, the Cybermen, having transformed the city into the Cyber Foundries, continued to evolve themselves and their technology in preparation for their final attack on the ship for complete control. (TV: The Doctor Falls) At an unknown point, they installed a Cyber-Planner into Floor 1056 to serve as their strategist and overall leader. In addition, a small team of CyberNeomorphs, including a Cyber-Leader and Cyber-Lieutenant, were sent to Floor 0508 to capture the two Masters for interrogation concerning the change to the Cybermen's definition of humanity; they were also tasked with preparing a swarm of Cybermats to attack Floor 0507. However, they were destroyed by Missy, and the Cybermats were forced back to Floor 1056. (PROSE: Alit in Underland)

Defeat
Hundreds of years later, the Cybermen had evolved into significantly more powerful forms; although several Mondasian Cybermen remained, many other Cybermen had evolved (TV: The Doctor Falls) into models resembling the Cybermen of the Cyber Legions (TV: A Good Man Goes to War) and the Cyberiad. (TV: Nightmare in Silver) After a lift containing a Cyberiad-type Cyberman was summoned to Floor 0507 by Missy, the Cyberman was destroyed by a combined attack from the Doctor, Missy, the Master and the converted Bill. Its death was alerted to the Cybermen on Floor 1056, who evolved even further to possess flight capabilities (TV: The Doctor Falls) reminiscent of those used by the Cybermen created by Missy on Earth, (TV: Death in Heaven) which the Cybermen used to fly en masse to Floor 0507. In the final battle, the Doctor, after ensuring that the humans were evacuated to Floor 0502, destroyed the Cyber-army by igniting all the fuel underneath Floor 0507 at once, incinerating the entire floor. In response, the few remaining Cybermen spent an unknown period of time preparing to attack Floor 0502, (TV: The Doctor Falls) although Nardole and the humans fought them off, to the point that, by the time Nardole died of old age on Floor 0502, the only remaining threats from Floor 1056 were swarms of Cybermats, which, from the perspectives of those living on the solar farm, only attacked every spring. (PROSE: Twice Upon a Time)