Highgate was an area of London. Gralstead House was located there. (AUDIO: The Ghosts of Gralstead)
In 2009 Gregory P. Wilkinson was living in a Victorian house in Highgate. Rani Chandra and Sarah Jane Smith visited him there because Rani wanted to do an interview with him. (AUDIO: Wraith World)
It was visited by the Twelfth Doctor and Clara Oswald. (COMIC: The Highgate Horror)