Floor 0508

Floor 0508, or more simply 508, was one of over a thousand decks on a Mondasian colony ship. (PROSE: Alit in Underland)

History
According to Nardole, it was full of gas lines which he was able to program to act as explosives during the Battle of Floor 0507. By detonating all of the gas lines, the Twelfth Doctor destroyed Floor 0507 at the end of the battle, destroying most of the Cybermen on the ship. (TV: The Doctor Falls)