Mount Everest was a mountain.
In 1953 the first humans successfully climbed Mount Everest. (TV: The Idiot's Lantern)
Santiago Jones visited it during one of his journeys. (TV: Death of the Doctor)
At some point during the 51st century, the Doctor helped carry the Mona Lisa up Mount Everest on a camel to preserve it from a war. (PROSE: The Art of Destruction)