Gettysburg
Gettysburg was a city in Pennsylvania, in the United States of America. In 1863, a major battle in the American Civil War was fought near Gettysburg. The Third Doctor and Charlie Fisher mapped the Confederate lines and delivered the information to the Union Army, which helped them win the battle. (COMIC: Backtime)
Shortly after the battle, President Abraham Lincoln delivered his Gettysburg Address. The First Doctor, Ian Chesterton, Barbara Wright and Vicki Pallister watched the speech on the Time-Space Visualiser. (TV: The Chase)
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 Gettysburg.
