Arcadia (city)

Arcadia was, according to the Eleventh Doctor, "Gallifrey's second city". (TV: The Day of the Doctor) During the Last Great Time War, it was thought to be "the safest place on Gallifrey". This was because it was protected by 400 sky trenches. Nevertheless, Dalek forces managed to breach these supposedly impregnable defences on the last day of the War, leading to the fall of the city. The War Doctor was present. (TV: The Last Day, The Day of the Doctor)

The Tenth Doctor later mentioned that he was present at the Fall of Arcadia during that war, and that he still hadn't gotten over it. (TV: Doomsday)