Tombstone, Arizona
From Tardis Wiki, the free Doctor Who reference
Tombstone was a town in the Arizona Territory in the United States of America. In October 1881, the First Doctor visited Tombstone in search of a dentist, who happened to be the gunfighter and gambler Doc Holliday. His companions Steven Taylor, Dodo Chaplet and he soon became involved in Holliday's feud with Ike Clanton and his brothers Billy and Phineas. (TV: The Gunfighters)
Location information
Though it's possible that a real world location doesn't exist in the same geographic space in the Doctor Who universe, such cases are few and far between. Thus, the map to the right is probably a good indicator of the DWU location of Tombstone, Arizona.