Arcadia (city)

Arcadia was known as "the safest place on Gallifrey" or "Second Capital of Gallifrey" during the Last Great Time War. It was attacked by the Daleks, who managed to breach the city's sky trenches. (TV: The Last Day) 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)

Three Doctors were there at Arcadia during 'The Fall of Arcadia'. (TV: The Day of The Doctor)