Washington, D.C.
From TARDIS Index File, the free Doctor Who reference.
Washington, D.C. is the capital city of the United States of America.
In 1865, the Sixth Doctor and Evelyn Smythe traveled to the city to fix history changes made by Robert Knox, including the assassination of Abraham Lincoln. (BFA: Assassin in the Limelight)
The Eighth Doctor found himself in Washington in 1951, not long after visiting Moscow in Russia. (NA: Endgame)
In 1997, the Prime Minister of the United Kingdom was assassinated there on the 6th of May. (NA: The Dying Days) Four years later, in September 2001, terrorists attacked the city.
In 2008, Alan Jackson was offered a job in the city and moved there with his daughter Maria Jackson from their old home in the Ealing district of London. (SJA: The Last Sontaran)
The Seventh Doctor visited the city and met Brigadier-General Adrienne Kramer there. (EDA: Vampire Science)
