Arcadia was a Human colony world in the 26th century. It was a non-technological paradise and served as a living specimen for a centuries-long experiment. (NA: Deceit)
Diamonds could be found on Arcadia and were very valuable. (TW: Kiss Kiss, Bang Bang)
The Fall of Arcadia was an important event during the Last Great Time War, where the planet fell to the Dalek Empire. (DW: Doomsday)
Amy Pond and The Doctor visited Arcadia. (DW: Vincent and the Doctor)