How did Doom end up in the year 2099?
Full details on what exactly happened to Doom were never revealed. He returned to Latveria in 2099 drained and powerless, raggedly standing upon the exact location of the ruins of Castle Doom, in a city now called simply Antikva Vilago, or “old village”. His memory of what happened is completely gone, although he does remember other details of his past such as his conflicts with the Fantastic Four. Later on, he remembers the decline of the age of Heroes, and he remembers killing Reed Richards. He also remembers growing old, and a tragedy of some kind of war that isn’t explained. It is explained that he had his memory tampered with at some time, but whether or not he is the Doctor Doom is never revealed.